Chapter 1

in practical astronomy which I could claim. In fact I had never been inside of an observatory, except on two or three occasions at Cambridge as a visitor. The captain reassured me by saying that no great experience was expected of a newcomer, and told me that I should go to work on the transit instrument under Professor Yarnall, to whose care I was then confided.

As the existence of a corps of professors of mathematics is peculiar to our navy, as well as an apparent, perhaps a real, anomaly, some account of it may be of interest. Early in the century--one hardly knows when the practice began--the Secretary of the Navy, in virtue of his general powers, used to appoint men as professors of mathematics in the navy, to go to sea and teach the midshipmen the art of navigation. In 1844, when work at the observatory was about to begin, no provision for astronomers was made by Congress. The most convenient way of supplying this want was to have the Secretary appoint professors of mathematics, and send them to the observatory on duty.

A few years later the Naval Academy was founded at Annapolis, and a similar course was pursued to provide it with a corps of instructors. Up to this time the professors had no form of appointment except a warrant from the Secretary of the Navy. Early in the history of the academy the midshipmen burned a professor in effigy. They were brought before a court-martial on the charge of disrespect to a superior officer, but pleaded that the professor, not holding a commission, was not their superior officer, and on this plea were acquitted. Congress thereupon took the matter up, provided that the number of professors should not exceed twelve, and that they should be commissioned by the President by and with the advice and consent of the Senate. This raised their rank to that of a commissioned corps in the navy. They were to perform such duty as the Secretary of the Navy might direct, and were, for the most part, divided between the Naval Academy and the Observatory.

During the civil war some complaint was made that the midshipmen coming from the academy were not well trained in the duties of a seagoing officer; and it was supposed that this was due to too much of their time being given to scientific studies. This was attributed to the professors, with the result that nearly all those attached to the academy were detached during the four years following the close of the civil war and ordered elsewhere, mostly to the observatory. Their places were taken by line officers who, in the intervals between their turns of sea duty, were made heads of departments and teachers of the midshipmen in nearly every branch.

This state of things led to the enactment of a law (in 1869, I think), "that hereafter no vacancy in the grade of professors of mathematics in the navy shall be filled."

In 1873 this provision was annulled by a law, again providing for a corps of twelve professors, three of whom should have the relative rank of captain, four of commander, and the remainder of lieutenant-commander or lieutenant.

Up to 1878 the Secretary of the Navy was placed under no restrictions as to his choice of a professor. He could appoint any citizen whom he supposed to possess the necessary qualifications. Then it was enacted that, before appointment, a candidate should pass a medical and a professional examination.

I have said that the main cause of hesitation in making my application arose from my aversion to very late night work. It soon became evident that there was less ground than I had supposed for apprehension on this point. There was a free and easy way of carrying on work which was surprising to one who had supposed it all arranged on strict plans, and done according to rule and discipline. Professor Yarnall, whose assistant I was, was an extremely pleasant gentleman to be associated with. Although one of the most industrious workers at the observatory, there was nothing of the martinet about him. He showed me how to handle the instrument and record my observations. There was a Nautical Almanac and a Catalogue of Stars. Out of these each of us could select what he thought best to observe.

The custom was that one of us should come on every clear evening, make observations as long as he chose, and then go home. The transit instrument was at one end of the building and the mural circle, in charge of Professor Hubbard, at the other. He was weak in health, and unable to do much continuous work of any kind, especially the hard work of observing. He and I arranged to observe on the same nights; but I soon found that there was no concerted plan between the two sets of observers. The instruments were old-fashioned ones, of which mine could determine only the right ascension of a star and his only its declination; hence to completely determine the position of a celestial body, observations must be made on the same object with both instruments. But I soon found that there was no concert of action of this kind. Hubbard, on the mural circle, had his plan of work; Yarnall and myself, on the transit, had ours. When either Hubbard or myself got tired, we could "vote it cloudy" and go out for a plate of oysters at a neighboring restaurant.

In justice to Captain Gilliss it must be said that he was not in any way responsible for this lack of system. It grew out of the origin and history of the establishment and the inaction of Congress. The desirableness of our having a national observatory of the same rank as those of other countries was pointed out from time to time by eminent statesmen from the first quarter of the century. John Quincy Adams had, both while he filled the presidential office and afterward, made active efforts in this direction; but there were grave doubts whether Congress had any constitutional authority to erect such an institution, and the project got mixed up with parties and politics. So strong was the feeling on the subject that, when the Coast Survey was organized, it was expressly provided that it should not establish an astronomical observatory.

The outcome of the matter was that, in 1842, when Congress at length decided that we should have our national observatory, it was not called such, but was designated as a "house" to serve as a depot for charts and instruments for the navy. But every one knew that an observatory was meant. Gilliss was charged with its erection, and paid a visit to Europe to consult with astronomers there on its design, and to order the necessary instruments. When he got through with this work and reported it as completed he was relieved, and Lieutenant Matthew F. Maury was appointed superintendent of the new institution.

Maury, although (as he wrote a few years later) quite without experience in the use of astronomical instruments, went at his work with great energy and efficiency, so that, for two or three years, the institution bade fair to take a high place in science. Then he branched off into what was, from a practical standpoint, the vastly more important work of studying the winds and currents of the ocean. The epoch-making character of his investigations in this line, and their importance to navigation when ships depended on sails for their motive power, were soon acknowledged by all maritime nations, and the fame which he acquired in pursuing them added greatly to the standing of the institution at which the work was done, though in reality an astronomical outfit was in no way necessary to it. The new work was so absorbing that he seemed to have lost interest in the astronomical side of the establishment, which he left to his assistants. The results were that on this side things fell into the condition I have described, and stayed there until Maury resigned his commission and cast his fortunes with the Confederacy. Then Gilliss took charge and had to see what could be done under the circumstances.

It soon became evident to him that no system of work of the first order of importance could be initiated until the instrumental equipment was greatly improved. The clocks, perfection in which is almost at the bottom of good work, were quite unfit for use. The astronomical clock with which Yarnall and I made our observations kept worse time than a high-class pocket watch does to-day. The instruments were antiquated and defective in several particulars. Before real work could be commenced new ones must be procured. But the civil war was in progress, and the times were not favorable to immediately securing them. That the work of the observatory was kept up was due to a feeling of pride on the part of our authorities in continuing it without interruption through the conflict. The personnel was as insufficient as the instruments. On it devolved not only the making of the astronomical observations, but the issue of charts and chronometers to the temporarily immense navy. In fact the observatory was still a depot of charts for the naval service, and continued to be such until the Hydrographic Office was established in 1866.

In 1863 Gilliss obtained authority to have the most pressing wants supplied by the construction of a great transit circle by Pistor and Martins in Berlin. He had a comprehensive plan of work with this instrument when it should arrive, but deferred putting any such plan in operation until its actual reception.

Somehow the work of editing, explaining, and preparing for the press the new series of observations made by Yarnall and myself with our old transit instrument devolved on me. To do this in the most satisfactory way, it was necessary to make a careful study of the methods and system at the leading observatories of other countries in the line we were pursuing, especially Greenwich. Here I was struck by the superiority of their system to ours. Everything was there done on an exact and uniform plan, and one which seemed to me better adapted to get the best results than ours was. For the non-astronomical reader it may be remarked that after an astronomer has made and recorded his observations, a large amount of calculation is necessary to obtain the result to which they lead. Making such calculations is called "reducing" the observations. Now in the previous history of the observatory, the astronomers fell into the habit of every one not only making his observations in his own way, but reducing them for himself. Thus it happened that Yarnall had been making and reducing his observations in his own way, and I, on alternate nights, had been making and reducing mine in my way, which was modeled after the Greenwich fashion, and therefore quite different from his. Now I suddenly found myself face to face with the problem of putting these two heterogeneous things together so as to make them look like a homogeneous whole. I was extremely mortified to see how poor a showing would be made in the eyes of foreign astronomers. But I could do nothing more than to describe the work and methods in such a way as to keep in the background the want of system that characterized them.

Notwithstanding all these drawbacks of the present, the prospect of future success seemed brilliant. Gilliss had the unlimited confidence of the Secretary of the Navy, had a family very popular in Washington society, was enthusiastically devoted to building up the work of the observatory, and was drawing around him the best young men that could be found to do that work. He made it a point that his relations with his scientific subordinates should be not only official, but of the most friendly social character. All were constantly invited to his charming family circle. It was from the occasional talks thus arising that I learned the details of his plan of work with the coming instrument.

In 1862 Gilliss had the working force increased by the appointment of four "aides," as they were then called,--a number that was afterwards reduced to three. This was the beginning of the corps of three assistant astronomers, which is still maintained. It will be of interest to know that the first aide was Asaph Hall; but before his appointment was made, an impediment, which for a time looked serious, had to be overcome. Gilliss desired that the aide should hold a good social and family position. The salary being only $1000, this required that he should not be married. Hall being married, with a growing family, his appointment was long objected to, and it was only through much persuasion on the part of Hubbard and myself that Gilliss was at length induced to withdraw his objections. Among other early appointees were William Harkness and John A. Eastman, whose subsequent careers in connection with the observatory are well known.

The death of Professor Hubbard in 1863 led to my taking his place, in charge of the mural circle, early in September of that year. This gave me an opportunity of attempting a little improvement in the arrangements. I soon became conscious of the fact, which no one had previously taken much account of, that upon the plan of each man reducing his own observations, not only was there an entire lack of homogeneity in the work, but the more work one did at night the more he had to do by day. It was with some trepidation that I presented the case to Gilliss, who speedily saw that work done with the instruments should be regarded as that of the observatory, and reduced on a uniform plan, instead of being considered as the property of the individual who happened to make it. Thus was introduced the first step toward a proper official system.

In February, 1865, the observatory sustained the greatest loss it had ever suffered, in the sudden death of its superintendent. What it would have grown to had he lived it is useless to guess, but there is little doubt that its history would have been quite different from what it is.

Soon afterward Admiral Davis left his position as Chief of the Bureau of Navigation to take the subordinate one of Superintendent of the Observatory. This step was very gratifying to me, Davis had not only a great interest in scientific work, especially astronomy, but a genuine admiration of scientific men which I have never seen exceeded, accompanied with a corresponding love of association with them and their work.

In October, 1865, occurred what was, in my eyes, the greatest event in the history of the observatory. The new transit circle arrived from Berlin in its boxes. Now for the first time in its history, the observatory would have a meridian instrument worthy of it, and would, it was hoped, be able to do the finest work in at least one branch of astronomy. To my great delight, Davis placed me in charge of it. The last three months of the year were taken up with mounting it in position and making those investigations of its peculiarities which are necessary before an instrument of the kind is put into regular use. On the 1st day of January, 1866, this was all done, and we were ready to begin operations. An opportunity thus arose of seeing what we could do in the way of a regular and well-planned piece of work. In the greater clearness of our sky, and the more southern latitude of our observatory, we had two great advantages over Greenwich. Looking back at his first two or three years of work at the observatory, Maury wrote to a friend, "We have beaten Greenwich hollow." It may be that I felt like trying to do the same thing over again. At any rate, I mapped out a plan of work the execution of which would require four years.

It was a piece of what, in astronomy, is called "fundamental work," in which results are to be obtained independent of any previously obtained by other observers. It had become evident to me from our own observations, as well as from a study of those made at European observatories, that an error in the right ascension of stars, so that stars in opposite quarters of the heavens would not agree, might very possibly have crept into nearly all the modern observations at Greenwich, Paris, and Washington. The determination of this error was no easy matter. It was necessary that, whenever possible, observations should be continued through the greater part of the twenty-four hours. One observer must be at work with comparative steadiness from nine o'clock in the morning until midnight or even dawn of the morning following. This requirement was, however, less exacting than might appear when stated. One half the nights would, as a general rule, be cloudy, and an observer was not expected to work on Sunday. Hence no one of the four observers would probably have to do such a day's work as this more than thirty or forty times in a year.

All this was hard work enough in itself, but conditions existed which made it yet harder. No houses were then provided for astronomers, and the observatory itself was situated in one of the most unhealthy parts of the city. On two sides it was bounded by the Potomac, then pregnant with malaria, and on the other two, for nearly half a mile, was found little but frame buildings filled with quartermaster's stores, with here and there a few negro huts. Most of the observers lived a mile or more from the observatory; during most of the time I was two miles away. It was not considered safe to take even an hour's sleep at the observatory. The result was that, if it happened to clear off after a cloudy evening, I frequently arose from my bed at any hour of the night or morning and walked two miles to the observatory to make some observation included in the programme.

This was certainly a new departure from the free and easy way in which we had been proceeding, and it was one which might be unwelcome to any but a zealous astronomer. As I should get the lion's share of credit for its results, whether I wanted to or not, my interest in the work was natural. But it was unreasonable to expect my assistants, one or two of whom had been raised to the rank of professor, to feel the same interest, and it is very creditable to their zeal that we pursued it for some time as well as we did. If there was any serious dissatisfaction with the duty, I was not informed of that fact.

During the second year of this work Admiral Davis was detached and ordered to sea. The question of a successor interested many besides ourselves. Secretary Welles considered the question what policy should be pursued in the appointment. Professor Henry took part in the matter by writing the secretary a letter, in which he urged the appointment of an astronomer as head of the institution. His position prevented his supporting any particular candidate; so he submitted a list of four names, any one of which would be satisfactory. These were: Professor William Chauvenet, Dr. B. A. Gould, Professor J. H. C. Coffin, U. S. N., and Mr. James Ferguson. The latter held a civil position at the observatory, under the title of "assistant astronomer," and was at the time the longest in service of any of its force.

A different view was urged upon the secretary in terms substantially these: "Professors so able as those of the observatory require no one to direct their work. All that the observatory really needs is an administrative head who shall preserve order, look after its business generally, and see that everything goes smoothly." Such a head the navy can easily supply.

The secretary allowed it to be given out that he would be glad to hear from the professors upon the subject. I thereupon went to him and expressed my preference for Professor Coffin. He asked me, "How would it do to have a purely administrative head?"

I replied that we might get along for a time if he did not interfere with our work.

"No," said the secretary, "he shall not interfere. That shall be understood."

As I left him there was, to my inexperienced mind, something very odd in this function, or absence of function, of the head of an establishment; but of course I had to bow to superior wisdom and could say nothing.

The policy of Commodore (afterward Rear-Admiral) Sands, the incoming superintendent, toward the professors was liberal in the last degree. Each was to receive due credit for what he did, and was in every way stimulated to do his best at any piece of scientific work he might undertake with the approval of the superintendent. Whether he wanted to observe an eclipse, determine the longitude of a town or interior station, or undertake some abstruse investigation, every facility for doing it and every encouragement to go on with it was granted him.

Under this policy the observatory soon reached the zenith of its fame and popularity. Whenever a total eclipse of the sun was visible in an accessible region parties were sent out to observe it. In 1869 three professors, I being one, were sent to Des Moines, Iowa, to observe the solar eclipse which passed across the country in June of that year. As a part of this work, I prepared and the observatory issued a detailed set of instructions to observers in towns at each edge of the shadow-path to note the short duration of totality. The object was to determine the exact point to which the shadow extended. At this same eclipse Professor Harkness shared with Professor Young of Princeton the honor of discovering the brightest line in the spectrum of the sun's corona. The year following parties were sent to the Mediterranean to observe an eclipse which occurred in December, 1870. I went to Gibraltar, although the observation of the eclipse was to me only a minor object. Some incidents connected with this European trip will be described in a subsequent chapter.

The reports of the eclipse parties not only described the scientific observations in great detail, but also the travels and experiences, and were sometimes marked by a piquancy not common in official documents. These reports, others pertaining to longitude, and investigations of various kinds were published in full and distributed with great liberality. All this activity grew out of the stimulating power and careful attention to business of the head of the observatory and the ability of the young professors of his staff. It was very pleasant to the latter to wear the brilliant uniform of their rank, enjoy the protection of the Navy Department, and be looked upon, one and all, as able official astronomers. The voice of one of our scientific men who returned from a visit abroad declaring that one of our eclipse reports was the laughing-stock of Europe was drowned in the general applause.

In the latter part of 1869 I had carried forward the work with the transit circle as far as it could be profitably pursued under existing conditions. On working up my observations, the error which I had suspected in the adopted positions of the stars was proved to be real. But the discovery of this error was due more to the system of observation, especially the pursuit of the latter through the day and night, than it was to any excellence of the instrument. The latter proved to have serious defects which were exaggerated by the unstable character of the clayey soil of the hill on which the observatory was situated. Other defects also existed, which seemed to preclude the likelihood that the future work of the instrument would be of a high class. I had also found that very difficult mathematical investigations were urgently needed to unravel one of the greatest mysteries of astronomy, that of the moon's motion. This was a much more important work than making observations, and I wished to try my hand at it. So in the autumn I made a formal application to the Secretary of the Navy to be transferred from the observatory to the Nautical Almanac Office for the purpose of engaging in researches on the motion of the moon. On handing this application to the superintendent he suggested that the work in question might just as well be done at the observatory. I replied that I thought that the business of the observatory was to make and reduce astronomical observations with its instruments, and that the making of investigations of the kind I had in view had always been considered to belong to the Nautical Almanac Office. He replied that he deemed it equally appropriate for the observatory to undertake it. As my objection was founded altogether on a principle which he refused to accept, and as by doing the work at the observatory I should have ready access to its library, I consented to the arrangement he proposed. Accordingly, in forwarding my application, he asked that my order should be so worded as not to detach me from the observatory, but to add the duty I asked for to that which I was already performing.

So far as I was personally concerned, this change was fortunate rather than otherwise. As things go in Washington, the man who does his work in a fine public building can gain consideration for it much more readily than if he does it in a hired office like that which the "Nautical Almanac" then occupied. My continued presence on the observatory staff led to my taking part in two of the great movements of the next ten years, the construction and inauguration of the great telescope and the observations of the transit of Venus. But for the time being my connection with the regular work of the observatory ceased.

On the retirement of Admiral Sands in 1874, Admiral Davis returned to the observatory, and continued in charge until his death in February, 1877. The principal event of this second administration was the dispatch of parties to observe the transit of Venus. Of this I shall speak in full in a subsequent chapter.

One incident, although of no public importance, was of some interest at the time. This was a visit of the only emperor who, I believe, had ever set foot on our shores,--Dom Pedro of Brazil. He had chosen the occasion of our Centennial for a visit to this country, and excited great interest during his stay, not only by throwing off all imperial reserve during his travels, but by the curiosity and vigor with which he went from place to place examining and studying everything he could find, and by the singular extent of his knowledge on almost every subject of a scientific or technical character. A Philadelphia engineer with whom he talked was quoted as saying that his knowledge of engineering was not merely of the ordinary kind to be expected in an intelligent man, but extended to the minutest details and latest improvements in the building of bridges, which was the specialty of the engineer in question.

Almost as soon as he arrived in Washington I received the following letter by a messenger from the Arlington Hotel:--

Mr.: En arrivant a Washington j'ai tout-de-suite songe a votre observatoire, ou vous avez acquis tant de droit a l'estime de tout ceux qui achevent la science. Je m'y rendrai donc aujourd'hui a 7 heures du soir, et je compte vous y trouver, surtout pour vous remercier de votre beau memoire que j'ai recu peu avant mon depart de mon pays, et que je n'ai pas pu, par consequent, apprecier autant que je l'aurais voulu. En me plaisant de l'espoir de vous connaitre personnellement je vous prie de me compter parmi vos affectionnes. D. Pedro D'Alcantara. 7 Mai, 1876.

Like other notes which I subsequently received from him, it was in his own autograph throughout: if he brought any secretary with him on his travels I never heard of it.

The letter placed me in an embarrassing position, because its being addressed to me was in contravention of all official propriety. Of course I lost no time in calling on him and trying to explain the situation. I told him that Admiral Davis, whom he well knew from his being in command of the Brazilian station a few years before, was the head of the observatory, and hinted as plainly as I could that a notification of the coming of such a visitor as he should be sent to the head of the institution. But he refused to take the hint, and indicated that he expected me to arrange the whole matter for him. This I did by going to the observatory and frankly explaining the matter to Admiral Davis. Happily the latter was not a stickler for official forms, and was cast in too large a mould to take offense where none was intended. At his invitation I acted as one of the receiving party. The carriage drove up at the appointed hour, and its occupant was welcomed by the admiral at the door with courtly dignity. The visitor had no time to spend in preliminaries; he wished to look through the establishment immediately.

The first object to meet his view was a large marble-cased clock which, thirty years before, had acquired some celebrity from being supposed to embody the first attempt to apply electricity to the recording of astronomical observations. It was said to have cost a large sum, paid partly as a reward to its inventor. Its only drawbacks were that it would not keep time and had never, so far as I am aware, served any purpose but that of an ornament. The first surprise came when the visitor got down on his hands and knees in front of the clock, reached his hands under it, and proceeded to examine its supports. We all wondered what it could mean. When he arose, it was explained. He did not see how a clock supported in this way could keep the exact time necessary in the work of an astronomer. So we had to tell him that the clock was not used for this purpose, and that he must wait until we visited the observing rooms to see our clocks properly supported.

The only evidence of the imperial will came out when he reached the great telescope. The moon, near first quarter, was then shining, but the night was more than half cloudy, and there was no hope of obtaining more than a chance glimpse at it through the clouds. But he wished to see the moon through the telescope. I replied that the sky was now covered, and it was very doubtful whether we should get a view of the moon. But he required that the telescope should be at once pointed at it. This was done, and at that moment a clear space appeared between the clouds. I remarked upon the fact, but he seemed to take it as a matter of course that the cloud would get out of the way when he wanted to look.

I made some remark about the "vernier" of one of the circles on the telescope.

"Why do you call it a vernier?" said he. "Its proper term is a nonius, because Nonius was its inventor and Vernier took the idea from him."

In this the national spirit showed itself. Nonius, a Portuguese, had invented something on a similar principle and yet essentially different from the modern vernier, invented by a Frenchman of that name.

Accompanying the party was a little girl, ten or twelve years old, who, though an interested spectator, modestly kept in the background and said nothing. On her arrival home, however, she broke her silence by running upstairs with the exclamation,--

"Oh, Mamma, he's the funniest emperor you ever did see!"

My connection with the observatory ceased September 15, 1877, when I was placed in charge of the Nautical Almanac Office. It may not, however, be out of place to summarize the measures which have since been taken both by the Navy Department and by eminent officers of the service to place the work of the institution on a sound basis. One great difficulty in doing this arises from the fact that neither Congress nor the Navy Department has ever stated the object which the government had in view in erecting the observatory, or assigned to it any well-defined public functions. The superintendent and his staff have therefore been left to solve the question what to do from time to time as best they could.

In the spring of 1877 Rear-Admiral John Rodgers became the superintendent of the observatory. As a cool and determined fighter during the civil war he was scarcely second even to Farragut, and he was at the same time one of the ablest officers and most estimable men that our navy ever included in its ranks. "I would rather be John Rodgers dead than any other man I know living," was said by one of the observatory assistants after his death. Not many months after his accession he began to consider the question whether the wide liberty which had been allowed the professors in choosing their work was adapted to attain success. The Navy Department also desired to obtain some expressions of opinion on the subject. The result was a discussion and an official paper, not emanating from the admiral, however, in which the duty of the head of the observatory was defined in the following terms:--

"The superintendent of the observatory should be a line officer of the navy, of high rank, who should attend to the business affairs of the institution, thus leaving the professors leisure for their proper work."

Although he did not entirely commit himself to this view, he was under the impression that to get the best work out of the professors their hearts must be in it; and this would not be the case if any serious restraint was placed upon them as to the work they should undertake.

After Rodgers's death Vice-Admiral Rowan was appointed superintendent. About this time it would seem that the department was again disposed to inquire into the results of the liberal policy heretofore pursued. Commander (since Rear-Admiral) William T. Sampson was ordered to the observatory, not as its head, but as assistant to the superintendent. He was one of the most proficient men in practical physics that the navy has ever produced. I believe that one reason for choosing so able and energetic an officer for the place was to see if any improvement could be made on the system. As I was absent at the Cape of Good Hope to observe the transit of Venus during the most eventful occasion of his administration, I have very little personal knowledge of it. It seems, however, that newspaper attacks were made on him, in which he was charged with taking possession of all the instruments of the observatory but two, and placing them in charge of naval officers who were not proficient in astronomical science. In reply he wrote an elaborate defense of his action to the "New York Herald," which appeared in the number for February 13, 1883. The following extract is all that need find a place in the present connection.

When I came here on duty a little more than a year since, I found these instruments disused. The transit instrument had not been used since 1878, and then only at intervals for several years previous; the mural circle had not been used since 1877; the prime vertical had not been used since 1867. These instruments had been shamefully neglected and much injured thereby. . . . The small equatorial and comet seeker were in the same disgraceful condition, and were unfit for any real work.

Admiral Franklin was made superintendent sometime in 1883, I believe, and issued an order providing that the work of the observatory should be planned by a board consisting of the superintendent, the senior line officer, and the senior professor. Professors or officers in charge of instruments were required to prepare a programme for their proposed work each year in advance, which programme would be examined by the board. Of the work of this board or its proceedings, no clear knowledge can be gleaned from the published reports, nor do I know how long it continued.

In 1885 Secretary Whitney referred to the National Academy of Sciences the question of the advisability of proceeding promptly with the erection of a new naval observatory upon the site purchased in 1880. The report of the academy was in the affirmative, but it was added that the observatory should be erected and named as a national one, and placed under civilian administration. The year following Congress made the preliminary appropriation for the commencement of the new building, but no notice was taken of the recommendation of the academy.

In 1891 the new buildings were approaching completion, and Secretary Tracy entered upon the question of the proper administration of the observatory. He discussed the subject quite fully in his annual report for that year, stating his conclusion in the following terms:--

I therefore recommend the adoption of legislation which shall instruct the President to appoint, at a sufficient salary, without restriction, from persons either within or outside the naval service, the ablest and most accomplished astronomer who can be found for the position of superintendent.

At the following session of Congress Senator Hale introduced an amendment to the naval appropriation bill, providing for the expenses of a commission to be appointed by the Secretary of the Navy, to consider and report upon the organization of the observatory. The House non-concurred in this amendment, and it was dropped from the bill.

At the same session, all the leading astronomers of the country united in a petition to Congress, asking that the recommendation of the Secretary of the Navy should be carried into effect. After a very patient hearing of arguments on the subject by Professor Boss and others, the House Naval Committee reported unanimously against the measure, claiming that the navy had plenty of officers able to administer the observatory in a satisfactory way, and that there was therefore no necessity for a civilian head.

Two years later, Senator Morrill offered an amendment to the legislative appropriation bill, providing that the superintendent of the observatory should be selected from civil life, and be learned in the science of astronomy. He supported his amendment by letters from a number of leading astronomers of the country in reply to questions which he had addressed to them.

This amendment, after being approved by the Senate Naval Committee, was referred by the Committee on Appropriations to the Secretary of the Navy. He recommended a modification of the measure so as to provide for the appointment of a "Director of Astronomy," to have charge of the astronomical work of the observatory, which should, however, remain under a naval officer as superintendent. This arrangement was severely criticised in the House by Mr. Thomas B. Reed, of Maine, and the whole measure was defeated in conference.

In 1892, when the new observatory was being occupied, the superintendent promulgated regulations for its work. These set forth in great detail what the observatory should do. Its work was divided into nine departments, each with its chief, besides which there was a chief astronomical assistant and a chief nautical assistant to the superintendent, making eleven chiefs in all. The duties of each chief were comprehensively described. As the entire scientific force of the observatory numbered some ten or twelve naval officers, professors, and assistant astronomers, with six computers, it may be feared that some of the nine departments were short-handed.

In September, 1894, new regulations were established by the Secretary of the Navy, which provided for an "Astronomical Director," who was to "have charge of and to be responsible for the direction, scope, character, and preparation for publication of all work purely astronomical, which is performed at the Naval Observatory." As there was no law for this office, it was filled first by the detail of Professor Harkness, who served until his retirement in 1899, then by the detail of Professor Brown, who served until March, 1901.

In 1899 the Secretary of the Navy appointed a Board of Visitors to the observatory, comprising Senator Chandler, of New Hampshire, Hon. A. G. Dayton, House of Representatives, and Professors Pickering, Comstock, and Hale. This board, "in order to obviate a criticism that the astronomical work of the observatory has not been prosecuted with that vigor and continuity of purpose which should be shown in a national observatory," recommended that the Astronomical Director and the Director of the Nautical Almanac should be civil officers, with sufficient salaries. A bill to this effect was introduced into each House of Congress at the next session, and referred to the respective naval committees, but never reported.

In 1901 Congress, in an amendment to the naval appropriation bill, provided a permanent Board of Visitors to the observatory, in whom were vested full powers to report upon its condition and expenditures, and to prescribe its plan of work. It was also provided in the same law that the superintendent of the observatory should, until further legislation by Congress, be a line officer of the navy of a rank not below that of captain. In the first annual report of this board is the following clause:--

"We wish to record our deliberate and unanimous judgment that the law should be changed so as to provide that the official head of the observatory--perhaps styled simply the Director--should be an eminent astronomer appointed by the President by and with the consent of the Senate."

Although the board still has a legal existence, Congress, in 1902, practically suspended its functions by declining to make any appropriation for its expenses. Moreover, since the detachment of Professor Brown, Astronomical Director, no one has been appointed to fill the vacancy thus arising. At the time of the present writing, therefore, the entire responsibility for planning and directing the work of the observatory is officially vested in the naval superintendent, as it was at the old observatory.

V

GREAT TELESCOPES AND THEIR WORK

One hardly knows where, in the history of science, to look for an important movement that had its effective start in so pure and simple an accident as that which led to the building of the great Washington telescope, and went on to the discovery of the satellites of Mars. Very different might have been a chapter of astronomical history, but for the accident of Mr. Cyrus Field, of Atlantic cable fame, having a small dinner party at the Arlington Hotel, Washington, in the winter of 1870. Among the guests were Senators Hamlin and Casserly, Mr. J. E. Hilgard of the Coast Survey, and a young son of Mr. Field, who had spent the day in seeing the sights of Washington. Being called upon for a recital of his experiences, the youth described his visit to the observatory, and expressed his surprise at finding no large telescope. The only instrument they could show him was much smaller and more antiquated than that of Mr. Rutherfurd in New York.

The guests listened to this statement with incredulity, and applied to Mr. Hilgard to know whether the visitor was not mistaken, through a failure to find the great telescope of the observatory. Mr. Hilgard replied that the statement was quite correct, the observatory having been equipped at a time when the construction of great refracting telescopes had not been commenced, and even their possibility was doubted.

"This ought not to be," said one of the senators. "Why is it so?"

Mr. Hilgard mentioned the reluctance of Congress to appropriate money for a telescope.

"It must be done," replied the senator. "You have the case properly represented to Congress, and we will see that an appropriation goes through the Senate at least."

It chanced that this suggestion had an official basis which was not known to the guests. Although Mr. Alvan Clark had already risen into prominence as a maker of telescopes, his genius in this direction had not been recognized outside of a limited scientific circle. The civil war had commenced just as he had completed the largest refracting telescope ever made, and the excitement of the contest, as well as the absorbing character of the questions growing out of the reconstruction of the Union, did not leave our public men much time to think about the making of telescopes. Mr. Clark had, however, been engaged by Captain Gilliss only a year or two after the latter had taken charge of the observatory, to come to Washington, inspect our instruments, and regrind their glasses. The result of his work was so striking to the observers using the instruments before and after his work on them, that no doubt of his ability could be felt. Accordingly, in preparing items for the annual reports of the observatory for the years 1868 and 1869, I submitted one to the superintendent setting forth the great deficiency of the observatory in respect to the power of its telescope, and the ability of Mr. Clark to make good that deficiency. These were embodied in the reports. It was recommended that authority be given to order a telescope of the largest size from Mr. Clark.

It happened, however, that Secretary Welles had announced in his annual reports as his policy that he would recommend no estimates for the enlargement and improvement of public works in his department, but would leave all matters of this kind to be acted on by Congress as the latter might deem best. As the telescope was thrown out of the regular estimates by this rule, this subject had failed to be considered by Congress.

Now, however, the fact of the recommendation appearing in the annual report, furnished a basis of action. Mr. Hilgard did not lose a day in setting the ball in motion.

He called upon me immediately, and I told him of the recommendations in the last two reports of the superintendent of the observatory. Together we went to see Admiral Sands, who of course took the warmest interest in the movement, and earnestly promoted it on the official side. Mr. Hilgard telegraphed immediately to some leading men of science, who authorized their signatures to a petition. In this paper attention was called to the wants of the observatory, as set forth by the superintendent, and to the eminent ability of the celebrated firm of the Clarks to supply them. The petition was printed and put into the hands of Senator Hamlin for presentation to the Senate only three or four days after the dinner party. The appropriation measure was formally considered by the Committee on Naval Affairs and that on Appropriations, and was adopted in the Senate as an amendment to the naval appropriation bill without opposition. The question then was to get the amendment concurred in by the House of Representatives. The session was near its close, and there was no time to do much work.

Several members of the House Committee on Appropriations were consulted, and the general feeling seemed to be favorable to the amendment. Great, therefore, was our surprise to find the committee recommending that the amendment be not concurred in. To prevent a possible misapprehension, I may remark that the present system of non-concurring in all amendments to an appropriation bill, in order to bring the whole subject into conference, had not then been introduced, so that this action showed a real opposition to the movement. One of the most curious features of the case is that the leader in the opposition was said to be Mr. Washburn, the chairman of the committee, who, not many years later, founded the Washburn Observatory of the University of Wisconsin. There is, I believe, no doubt that his munificence in this direction arose from what he learned about astronomy and telescopes in the present case.

It happened, most fortunately, that the joint committee of conference included Drake of the Senate and Niblack of the House, both earnestly in favor of the measure. The committee recommended concurrence, and the clause authorizing the construction became a law. The price was limited to $50,000, and a sum of $10,000 was appropriated for the first payment.

No sooner were the Clarks consulted than difficulties were found which, for a time, threatened to complicate matters, and perhaps delay the construction. In the first place, our currency was then still on a paper basis. Gold was at a premium of some ten or fifteen per cent., and the Clarks were unwilling to take the contract on any but a gold basis. This, of course, the Government could not do. But the difficulty was obviated through the action of a second one, which equally threatened delay. Mr. L. J. McCormick, of reaping-machine fame, had conceived the idea of getting the largest telescope that could be made. He had commenced negotiations with the firm of Alvan Clark & Sons before we had moved, and entered into a contract while the appropriation was still pending in Congress. If the making of one great telescope was a tedious job, requiring many years for its completion, how could two be made?

I was charged with the duty of negotiating the government contract with the Clarks. I found that the fact of Mr. McCormick's contract being on a gold basis made them willing to accept one from the Government on a currency basis; still they considered that Mr. McCormick had the right of way in the matter of construction, and refused to give precedence to our instrument. On mature consideration, however, the firm reached the conclusion that two instruments could be made almost simultaneously, and Mr. McCormick very generously waived any right he might have had to precedence in the matter.

The question how large an instrument they would undertake was, of course, one of the first to arise. Progress in the size of telescopes had to be made step by step, because it could never be foreseen how soon the limit might be met; and if an attempt were made to exceed it, the result would be not only failure for the instrument, but loss of labor and money by the constructors. The largest refracting telescope which the Clarks had yet constructed was one for the University of Mississippi, which, on the outbreak of the civil war, had come into the possession of the Astronomical Society of Chicago. This would have been the last step, beyond which the firm would not have been willing to go to any great extent, had it not happened that, at this very time, a great telescope had been mounted in England. This was made by Thomas Cooke & Sons of York, for Mr. R. S. Newall of Gateshead on Tyne, England. The Clarks could not, of course, allow themselves to be surpassed or even equaled by a foreign constructor; yet they were averse to going much beyond the Cooke telescope in size. Twenty-six inches aperture was the largest they would undertake. I contended as strongly as I could for a larger telescope than Mr. McCormick's, but they would agree to nothing of the sort,--the supposed right of that gentleman to an instrument of equal size being guarded as completely as if he had been a party to the negotiations. So the contract was duly made for a telescope of twenty-six inches clear aperture.

At that time Cooke and Clark were the only two men who had ever succeeded in making refracting telescopes of the largest size. But in order to exercise their skill, an art equally rare and difficult had to be perfected, that of the glassmaker. Ordinary glass, even ordinary optical glass, would not answer the purpose at all. The two disks, one of crown glass and the other of flint, must be not only of perfect transparency, but absolutely homogeneous through and through, to avoid inequality of refraction, and thus cause all rays passing through them to meet in the same focus. It was only about the beginning of the century that flint disks of more than two or three inches diameter could be made. Even after that, the art was supposed to be a secret in the hands of a Swiss named Guinand, and his family. Looking over the field, the Clarks concluded that the only firm that could be relied on to furnish the glass was that of Chance & Co., of Birmingham, England. So, as soon as the contracts were completed, one of the Clark firm visited England and arranged with Chance & Co. to supply the glass for the two telescopes. The firm failed in a number of trials, but by repeated efforts finally reached success at the end of a year. The glasses were received in December, 1871, and tested in the following month. A year and a half more was required to get the object glasses into perfect shape; then, in the spring or summer of 1873, I visited Cambridge for the purpose of testing the glasses. They were mounted in the yard of the Clark establishment in a temporary tube, so arranged that the glass could be directed to any part of the heavens.

I have had few duties which interested me more than this. The astronomer, in pursuing his work, is not often filled with those emotions which the layman feels when he hears of the wonderful power of the telescope. Not to say anything so harsh as that "familiarity breeds contempt," we must admit that when an operation of any sort becomes a matter of daily business, the sentiments associated with it necessarily become dulled. Now, however, I was filled with the consciousness that I was looking at the stars through the most powerful telescope that had ever been pointed at the heavens, and wondered what mysteries might be unfolded. The night was of the finest, and I remember, sweeping at random, I ran upon what seemed to be a little cluster of stars, so small and faint that it could scarcely have been seen in a smaller instrument, yet so distant that the individual stars eluded even the power of this instrument. What cluster it might have been it was impossible to determine, because the telescope had not the circles and other appliances necessary for fixing the exact location of an object. I could not help the vain longing which one must sometimes feel under such circumstances, to know what beings might live on planets belonging to what, from an earthly point of view, seemed to be a little colony on the border of creation itself.

In his report dated October 9, 1873, Admiral Sands reported the telescope as "nearly completed." The volume of Washington observations showed that the first serious observations made with it, those on the satellites of Neptune, were commenced on November 10 of the same year. Thus, scarcely more than a month elapsed from the time that the telescope was reported still incomplete in the shop of its makers until it was in regular nightly use.

Associated with the early history of the instrument is a chapter of astronomical history which may not only instruct and amuse the public, but relieve the embarrassment of some astronomer of a future generation who, reading the published records, will wonder what became of an important discovery. If the faith of the public in the absolute certainty of all astronomical investigation is thereby impaired, what I have to say will be in the interest of truth; and I have no fear that our science will not stand the shock of the revelation. Of our leading astronomical observers of the present day--of such men as Burnham and Barnard--it may be safely said that when they see a thing it is there. But this cannot always be said of every eminent observer, and here is a most striking example of this fact.

When the telescope was approaching completion I wrote to the head of one of the greatest European observatories, possessing one of the best telescopes of the time, that the first thing I should attempt with the telescope would be the discovery of the companion of Procyon. This first magnitude star, which may be well seen in the winter evenings above Orion, had been found to move in an exceedingly small orbit, one too small to be detected except through the most refined observations of modern precision. The same thing had been found in the case of Sirius, and had been traced to the action of a minute companion revolving around it, which was discovered by the Clarks a dozen years before. There could be no doubt that the motion of Procyon was due to the same cause, but no one had ever seen the planet that produced it, though its direction from the star at any time could be estimated.

Now, it happened that my European friend, as was very natural, had frequently looked for this object without seeing it. Whether my letter set him to looking again, or whether he did not receive it until a later day, I do not know. What is certain is that, in the course of the summer, he published the discovery of the long-looked-for companion, supplemented by an excellent series of observations upon it, made in March and April.

Of course I was a little disappointed that the honor of first finding this object did not belong to our own telescope. Still I was naturally very curious to see it. So, on the very first night on which the telescope could be used, I sat up until midnight to take a look at Procyon, not doubting that, with the greater power of our telescope, it would be seen at the first glance. To my great concern, nothing of the sort was visible. But the night was far from good, the air being somewhat thick with moisture, which gave objects seen through it a blurred appearance; so I had to await a better night and more favorable conditions. Better nights came and passed, and still not a trace of the object could be seen. Supposing that the light of the bright star might be too dazzling, I cut it off with a piece of green glass in the focus. Still no companion showed itself. Could it be that our instrument, in a more favorable location, would fail to show what had been seen with one so much smaller? This question I could not answer, but wrote to my European friend of my unavailing attempts.

He replied expressing his perplexity and surprise at the occurrence, which was all the greater that the object had again been seen and measured in April, 1874. A fine-looking series of observations was published, similar to those of the preceding year. What made the matter all the more certain was that there was a change in the direction of the object which corresponded very closely to the motion as it had been predicted by Auwers. The latter published a revision of his work, based on the new observations.

A year later, the parties that had been observing the transit of Venus returned home. The head of one of them, Professor C. H. F. Peters of Clinton, stopped a day or two at Washington. It happened that a letter from my European friend arrived at the same time. I found that Peters was somewhat skeptical as to the reality of the object. Sitting before the fire in my room at the observatory, I read to him and some others extracts from the letter, which cited much new evidence to show the reality of the discovery. Not only had several of his own observers seen the object, but it had been seen and measured on several different nights by a certain Professor Blank, with a telescope only ten or twelve inches aperture.

"What," said Peters, "has Blank seen it?"

"Yes, so the letter says."

"Then it is n't there!"

And it really was not there. The maker of the discovery took it all back, and explained how he had been deceived. He found that the telescope through which the observations were made seemed to show a little companion of the same sort alongside of every very bright star. Everything was explained by this discovery. Even the seeming motion of the imaginary star during the twelve months was accounted for by the fact that in 1873 Procyon was much nearer the horizon when the observations were made than it was the year following. [1]

There is a sequel to the history, which may cause its revision by some astronomer not many years hence. When the great telescope was mounted at the Lick Observatory, it is understood that Burnham and Barnard, whose eyes are of the keenest, looked in vain for the companion of Procyon. Yet, in 1895, it was found with the same instrument by Schaeberle, and has since been observed with the great Yerkes telescope, as well as by the observers at Mount Hamilton, so that the reality of the discovery is beyond a doubt. The explanation of the failure of Burnham and Barnard to see it is very simple: the object moves in an eccentric orbit, so that it is nearer the planet at some points of its orbit than at others. It was therefore lost in the rays of the bright star during the years 1887-94. Is it possible that it could have been far enough away to be visible in 1873-74? I need scarcely add that this question must be answered in the negative, yet it may be worthy of consideration, when the exact orbit of the body is worked out twenty or thirty years hence.

In my work with the telescope I had a more definite end in view than merely the possession of a great instrument. The work of reconstructing the tables of the planets, which I had long before mapped out as the greatest one in which I should engage, required as exact a knowledge as could be obtained of the masses of all the planets. In the case of Uranus and Neptune, the two outer planets, this knowledge could best be obtained by observations on their satellites. To the latter my attention was therefore directed. In the case of Neptune, which has only one satellite yet revealed to human vision, and that one so close to the planet that the observations are necessarily affected by some uncertainty, it was very desirable that a more distant one should be found if it existed. I therefore during the summer and autumn of 1874 made most careful search under the most favorable conditions. But no second satellite was found. I was not surprised to learn that the observers with the great Lick telescope were equally unsuccessful. My observations with the instrument during two years were worked up and published, and I turned the instrument over to Professor Hall in 1875.

The discovery of the satellites of Mars was made two years later, in August, 1877. As no statement that I took any interest in the discovery has ever been made in any official publication, I venture, with the discoverer's permission, to mention the part that I took in verifying it.

One morning Professor Hall confidentially showed me his first observations of an object near Mars, and asked me what I thought of them. I remarked, "Why, that looks very much like a satellite."

Yet he seemed very incredulous on the subject; so incredulous that I feared he might make no further attempt to see the object. I afterward learned, however, that this was entirely a misapprehension on my part. He had been making a careful search for some time, and had no intention of abandoning it until the matter was cleared up one way or the other.

The possibility of the object being an asteroid suggested itself. I volunteered to test this question by looking at the ephemerides of all the small planets in the neighborhood of Mars. A very little searching disproved the possibility of the object belonging to this class. One such object was in the neighborhood, but its motion was incompatible with the measures.

Then I remarked that, if the object were really a satellite, the measures already made upon it, and the approximately known mass of the planet, would enable the motion of the satellite to be determined for a day or two. Thus I found that on that night the satellite would be hidden in the early evening by the planet, but would emerge after midnight. I therefore suggested to Professor Hall that, if it was not seen in the early evening, he should wait until after midnight. The result was in accordance with the prediction,--the satellite was not visible in the early evening, but came out after midnight. No further doubt was possible, and the discovery was published. The labor of searching and observing was so exhausting that Professor Hall let me compute the preliminary orbit of the satellites from his early observations.

My calculations and suggestions lost an importance they might otherwise have claimed, for the reason that several clear nights followed. Had cloudy weather intervened, a knowledge of when to look for the object might have greatly facilitated its recognition.

It is still an open question, perhaps, whether a great refracting telescope will last unimpaired for an indefinite length of time. I am not aware that the twin instruments of Harvard and Pulkowa, mounted in 1843, have suffered from age, nor am I aware that any of Alvan Clark's instruments are less perfect to-day than when they left the hands of their makers. But not long after the discovery of the satellites of Mars, doubts began to spread in some quarters as to whether the great Washington telescope had not suffered deterioration. These doubts were strengthened in the following way: When hundreds of curious objects were being discovered in the heavens here and there, observers with small instruments naturally sought to find them. The result was several discoveries belonging to the same class as that of the satellite of Procyon. They were found with very insignificant instruments, but could not be seen in the large ones. Professor Hall published a letter in a European journal, remarking upon the curious fact that several objects were being discovered with very small instruments, which were invisible in the Washington telescope. This met the eye of Professor Wolf, a professor at the Sorbonne in Paris, as well as astronomer at the Paris Observatory. In a public lecture, which he delivered shortly afterward, he lamented the fact that the deterioration of the Washington telescope had gone so far as that, and quoted Professor Hall as his authority.

The success of the Washington telescope excited such interest the world over as to give a new impetus to the construction of such instruments. Its glass showed not the slightest drawbacks from its great size. It had been feared that, after a certain limit, the slight bending of the glass under its own weight would be injurious to its performance. Nothing of the kind being seen, the Clarks were quite ready to undertake much larger instruments. A 30-inch telescope for the Pulkova Observatory in Russia, the 36-inch telescope of the Lick Observatory in California, and, finally, the 40-inch of the Yerkes Observatory in Chicago, were the outcome of the movement.

Of most interest to us in the present connection is the history of the 30-inch telescope of the Pulkova Observatory, the object glass of which was made by Alvan Clark & Sons. It was, I think, sometime in 1878 that I received a letter from Otto Struve, [2] director of the Pulkova Observatory, stating that he was arranging with his government for a grant of money to build one of the largest refracting telescopes. In answering him I called his attention to the ability of Alvan Clark & Sons to make at least the object glass, the most delicate and difficult part of the instrument. The result was that, after fruitless negotiations with European artists, Struve himself came to America in the summer of 1879 to see what the American firm could do. He first went to Washington and carefully examined the telescope there. Then he proceeded to Cambridge and visited the workshop of the Clarks. He expressed some surprise at its modest dimensions and fittings generally, but was so well pleased with what he saw that he decided to award them the contract for making the object glass. He was the guest of the Pickerings at the Cambridge Observatory, and invited me thither from where I was summering on the coast of Massachusetts to assist in negotiating the contract.

He requested that, for simplicity in conference, the preliminary terms should be made with but a single member of the firm to talk with. George B. Clark, the eldest member, was sent up to represent the firm. I was asked to take part in the negotiations as a mutual friend of both parties, and suggested the main conditions of the contract. A summary of these will be found in the publication to which I have already referred.

There was one provision the outcome of which was characteristic of Alvan Clark & Sons. Struve, in testing some object glasses which they had constructed and placed in their temporary tube, found so great physical exertion necessary in pointing so rough an instrument at any heavenly body with sufficient exactness, that he could not form a satisfactory opinion of the object glass. As he was to come over again when the glass was done, in order to test it preliminary to acceptance, he was determined that no such difficulty should arise. He therefore made a special provision that $1000 extra, to be repaid by him, should be expended in making a rough equatorial mounting in which he could test the instrument. George Clark demurred to this, on the ground that such a mounting as was necessary for this purpose could not possibly cost so much money. But Struve persistently maintained that one to cost $1000 should be made. The other party had to consent, but failed to carry out this provision. The tube was, indeed, made large enough to test not only Struve's glass but the larger one of the Lick Observatory, which, though not yet commenced, was expected to be ready not long afterward. Yet, notwithstanding this increase of size, I think the extra cost turned out to be much less than $1000, and the mounting was so rough that when Struve came over in 1883 to test the glass, he suffered much physical inconvenience and met, if my memory serves me aright, with a slight accident, in his efforts to use the rough instrument.

In points like this I do not believe that another such business firm as that of the Clarks ever existed in this country or any other. Here is an example. Shortly before the time of Struve's visit, I had arranged with them for the construction of a refined and complicated piece of apparatus to measure the velocity of light. As this apparatus was quite new in nearly all its details, it was impossible to estimate in advance what it might cost; so, of course, they desired that payment for it should be arranged on actual cost after the work was done. I assured them that the government would not enter into a contract on such terms. There must be some maximum or fixed price. This they fixed at $2500. I then arranged with them that this should be taken as a maximum and that, if it was found to cost less, they should accept actual cost. The contract was arranged on this basis. There were several extras, including two most delicate reflecting mirrors which would look flat to the eye, but were surfaces of a sphere of perhaps four miles diameter. The entire cost of the apparatus, as figured up by them after it was done, with these additions, was less than $1500, or about forty per cent. below the contract limit.

No set of men were ever so averse to advertising themselves. If anybody, in any part of the world, wanted them to make a telescope, he must write to them to know the price, etc. They could never be induced to prepare anything in the form of a price catalogue of the instruments they were prepared to furnish. The history of their early efforts and the indifference of our scientific public to their skill forms a mortifying chapter in our history of the middle of the century. When Mr. Clark had finished his first telescope, a small one of four inches aperture, which was, I have no reason to doubt, the best that human art could make, he took it to the Cambridge Observatory to be tested by one of the astronomers. The latter called his attention to a little tail which the glass showed as an appendage of a star, and which was, of course, non-existent. It was attributed to a defect in the glass, which was therefore considered a failure. Mr. Clark was quite sure that the tail was not shown when he had previously used the glass, but he could not account for it at the time. He afterwards traced it to the warm air collecting in the upper part of the tube and producing an irregular refraction of the light. When this cause was corrected the defect disappeared. But he got no further encouragement at home to pursue his work. The first recognition of his genius came from England, the agent being Rev. W. R. Dawes, an enthusiastic observer of double stars, who was greatly interested in having the best of telescopes. Mr. Clark wrote him a letter describing a number of objects which he had seen with telescopes of his own make. From this description Mr. Dawes saw that the instruments must be of great excellence, and the outcome of the matter was that he ordered one or more telescopes from the American maker. Not until then were the abilities of the latter recognized in his own country.

I have often speculated as to what the result might have been had Mr. Clark been a more enterprising man. If, when he first found himself able to make a large telescope, he had come to Washington, got permission to mount his instrument in the grounds of the capitol, showed it to members of Congress, and asked for legislation to promote this new industry, and, when he got it, advertised himself and his work in every way he could, would the firm which he founded have been so little known after the death of its members, as it now unhappily is? This is, perhaps, a rather academic question, yet not an unprofitable one to consider.

In recent years the firm was engaged only to make object glasses of telescopes, because the only mountings they could be induced to make were too rude to satisfy astronomers. The palm in this branch of the work went to the firm of Warner & Swasey, whose mounting of the great Yerkes telescope of the University of Chicago is the last word of art in this direction.

During the period when the reputation of the Cambridge family was at its zenith, I was slow to believe that any other artist could come up to their standard. My impression was strengthened by a curious circumstance. During a visit to the Strasburg Observatory in 1883 I was given permission to look through its great telescope, which was made by a renowned German artist. I was surprised to find the object glass affected by so serious a defect that it could not be expected to do any work of the first class. One could only wonder that European art was so backward. But, several years afterward, the astronomers discovered that, in putting the glasses together after being cleaned, somebody had placed one of them in the wrong position, the surface which should have been turned toward the star being now turned toward the observer. When the glass was simply turned over so as to have the right face outward, the defect disappeared.

[1] In justice to Mr. Blank, I must say that there seems to have been some misunderstanding as to his observations. What he had really seen and observed was a star long well known, much more distant from Procyon than the companion in question.

[2] Otto Struve was a brother of the very popular Russian minister to Washington during the years 1882-92. He retired from the direction of the Pulkowa Observatory about 1894. The official history of his negotiations and other proceedings for the construction of the telescope will be found in a work published in 1889 in honor of the jubilee of the observatory.

VI

THE TRANSITS OF VENUS

It was long supposed that transits of Venus over the sun's disk afforded the only accurate method of determining the distance of the sun, one of the fundamental data of astronomy. Unfortunately, these phenomena are of the rarest. They come in pairs, with an interval of eight years between the transits of a pair. A pair occurred in 1761 and 1769, and again in 1874 and 1882. Now the whole of the twentieth century will pass without another recurrence of the phenomenon. Not until the years 2004 and 2012 will our posterity have the opportunity of witnessing it.

Much interesting history is associated with the adventures of the astronomers who took part in the expeditions to observe the transits of 1761 and 1769. In the almost chronic warfare which used to rage between France and England during that period, neither side was willing to regard as neutral even a scientific expedition sent out by the other. The French sent one of their astronomers, Le Gentil, to observe the transit at Pondicherry in the East Indies. As he was nearing his station, the presence of the enemy prevented him from making port, and he was still at sea on the day of the transit. When he at length landed, he determined to remain until the transit of 1769, and observe that. We must not suppose, however, that he was guilty of the eccentricity of doing this with no other object in view than that of making the observation. He found the field open for profitable mercantile enterprise, as well as interesting for scientific observations and inquiries. The eight long years passed away, and the morning of June 4, 1769, found him in readiness for his work. The season had been exceptionally fine. On the morning of the transit the sun shone in a cloudless sky, as it had done for several days previous. But, alas for all human hopes! Just before Venus reached the sun, the clouds gathered, and a storm burst upon the place. It lasted until the transit was over, and then cleared away again as if with the express object of showing the unfortunate astronomer how helpless he was in the hands of the elements.

The Royal Society of England procured a grant of L800 from King George II. for expeditions to observe the transit of 1761. [1] With this grant the Society sent the Rev. Nevil Maskelyne to the island of St. Helena, and, receiving another grant, it was used to dispatch Messrs. Mason and Dixon (those of our celebrated "line") to Bencoolen. The admiralty also supplied a ship for conveying the observers to their respective destinations. Maskelyne, however, would not avail himself of this conveyance, but made his voyage on a private vessel. Cloudy weather prevented his observations of the transit, but this did not prevent his expedition from leaving for posterity an interesting statement of the necessaries of an astronomer of that time. His itemized account of personal expenses was as follows:--

One year's board at St. Helena . . L109 10s. 0d. Liquors at 5s. per day . . . . 91 5 0 Washing at 9d. per day . . . . 13 13 9 Other expenses . . . . . . 27 7 6 Liquors on board ship for six months 50 0 0 --- --- --- L291 16s. 3d.

Seven hundred dollars was the total cost of liquors during the eighteen months of his absence. Admiral Smyth concludes that Maskelyne "was not quite what is now ycleped a teetotaler." He was subsequently Astronomer Royal of England for nearly half a century, but his published observations give no indication of the cost of the drinks necessary to their production.

Mason and Dixon's expedition met with a mishap at the start. They had only got fairly into the English Channel when their ship fell in with a French frigate of superior force. An action ensued in which the English crew lost eleven killed and thirty-eight wounded. The Frenchman was driven off, but the victorious vessel had to return to Plymouth for repairs. This kind of a scientific expedition was more than the astronomers had bargained for, and they wrote from Plymouth to the Royal Society, describing their misfortune and resigning their mission. But the Council of the Society speedily let them know that they were unmoved by the misfortunes of their scientific missionaries, and pointed out to them in caustic terms that, having solemnly undertaken the expedition, and received money on account of it, their failure to proceed on the voyage would be a reproach to the nation in general, and to the Royal Society in particular. It would also bring an indelible scandal upon their character, and probably end in their utter ruin. They were assured that if they persisted in the refusal, they would be treated with the most inflexible resentment, and prosecuted with the utmost severity of the law.

Under such threats the unfortunate men could do nothing but accept the situation and sail again after their frigate had been refitted. When they got as far as the Cape of Good Hope, it was found very doubtful whether they would reach their destination in time for the transit; so, to make sure of some result from their mission, they made their observations at the Cape.

One of the interesting scraps of history connected with the transit of 1769 concerns the observations of Father Maximilian Hell, S. J., the leading astronomer of Vienna. He observed the transit at Wardhus, a point near the northern extremity of Norway, where the sun did not set at the season of the transit. Owing to the peculiar circumstances under which the transit was observed,--the ingress of the planet occurring two or three hours before the sun approached the northern horizon, and the end of the transit about as long afterward,--this station was the most favorable one on the globe. Hell, with two or three companions, one of them named Sajnovics, went on his mission to this isolated place under the auspices of the king of Denmark. The day was cloudless and the observations were made with entire success. He returned to Copenhagen, where he passed several months in preparing for the press a complete account of his expedition and the astronomical observations made at the station.

Astronomers were impatient to have the results for the distance of the sun worked out as soon as possible. Owing to the importance of Hell's observations, they were eagerly looked for. But he at first refused to make them known, on the ground that, having been made under the auspices of the king of Denmark, they ought not to be made known in advance of their official publication by the Danish Academy of Sciences. This reason, however, did not commend itself to the impatient astronomers; and suspicions were aroused that something besides official formalities was behind the delay. It was hinted that Hell was waiting for the observations made at other stations in order that he might so manipulate his own that they would fit in with those made elsewhere. Reports were even circulated that he had not seen the transit at all, owing to cloudy weather, and that he was manufacturing observations in Copenhagen. The book was, however, sent to the printer quite promptly, and the insinuations against its author remained a mere suspicion for more than sixty years. Then, about 1833, a little book was published on the subject by Littrow, Director of the Vienna Observatory, which excited much attention. Father Hell's original journal had been conveyed to Vienna on his return, and was still on deposit at the Austrian National Observatory. Littrow examined it and found, as he supposed, that the suspicions of alterations in observations were well founded; more especially that the originals of the all-important figures which recorded the critical moment of "contact" had been scraped out of the paper, and new ones inserted in their places. The same was said to be the case with many other important observations in the journal, and the conclusion to which his seemingly careful examination led was that no reliance could be placed on the genuineness of Hell's work. The doubts thus raised were not dispelled until another half-century had elapsed.

In 1883 I paid a visit to Vienna for the purpose of examining the great telescope which had just been mounted in the observatory there by Grubb, of Dublin. The weather was so unfavorable that it was necessary to remain two weeks, waiting for an opportunity to see the stars. One evening I visited the theatre to see Edwin Booth, in his celebrated tour over the Continent, play King Lear to the applauding Viennese. But evening amusements cannot be utilized to kill time during the day. Among the tasks I had projected was that of rediscussing all the observations made on the transits of Venus which had occurred in 1761 and 1769, by the light of modern science. As I have already remarked, Hell's observations were among the most important made, if they were only genuine. So, during my almost daily visits to the observatory, I asked permission of Director Weiss to study Hell's manuscript.

At first the task of discovering anything which would lead to a positive decision on one side or the other seemed hopeless. To a cursory glance, the descriptions given by Littrow seemed to cover the ground so completely that no future student could turn his doubt into certainty. But when one looks leisurely at an interesting object, day after day, he continually sees more and more. Thus it was in the present case. One of the first things to strike me as curious was that many of the alleged alterations had been made before the ink got dry. When the writer made a mistake, he had rubbed it out with his finger, and made a new entry.

The all-important point was a certain suspicious record which Littrow affirmed had been scraped out so that the new insertion could be made. As I studied these doubtful figures, day by day, light continually increased. Evidently the heavily written figures, which were legible, had been written over some other figures which were concealed beneath them, and were, of course, completely illegible, though portions of them protruded here and there outside of the heavy figures. Then I began to doubt whether the paper had been scraped at all. To settle the question, I found a darkened room, into which the sun's rays could be admitted through an opening in the shutter, and held the paper in the sunlight in such a way that the only light which fell on it barely grazed the surface of the paper. Examining the sheet with a magnifying glass, I was able to see the original texture of the surface with all its hills and hollows. A single glance sufficed to show conclusively that no eraser had ever passed over the surface, which had remained untouched.

The true state of the case seemed to me almost beyond doubt. It frequently happened that the ink did not run freely from the pen, so that the words had sometimes to be written over again. When Hell first wrote down the little figures on which, as he might well suppose, future generations would have to base a very important astronomical element, he saw that they were not written with a distinctness corresponding to their importance. So he wrote them over again with the hand, and in the spirit of a man who was determined to leave no doubt on the subject, little weening that the act would give rise to a doubt which would endure for a century.

This, although the most important case of supposed alteration, was by no means the only one. Yet, to my eyes, all the seeming corrections in the journal were of the most innocent and commonplace kind,--such as any one may make in writing.

Then I began to compare the manuscript, page after page, with Littrow's printed description. It struck me as very curious that where the manuscript had been merely retouched with ink which was obviously the same as that used in the original writing, but looked a little darker than the original, Littrow described the ink as of a different color. In contrast with this, there was an important interlineation, which was evidently made with a different kind of ink, one that had almost a blue tinge by comparison; but in the description he makes no mention of this plain difference. I thought this so curious that I wrote in my notes as follows:--

"That Littrow, in arraying his proofs of Hell's forgery, should have failed to dwell upon the obvious difference between this ink and that with which the alterations were made leads me to suspect a defect in his sense of color."

Then it occurred to me to inquire whether, perhaps, such could have been the case. So I asked Director Weiss whether anything was known as to the normal character of Littrow's power of distinguishing colors. His answer was prompt and decisive. "Oh, yes, Littrow was color blind to red. He could not distinguish between the color of Aldebaran and that of the whitest star." No further research was necessary. For half a century the astronomical world had based an impression on the innocent but mistaken evidence of a color-blind man respecting the tints of ink in a manuscript.

About the middle of the nineteenth century other methods of measuring the sun's distance began to be developed which, it was quite possible, might prove as good as the observation in question. But the relative value of these methods and of transits of Venus was a subject on which little light could be thrown; and the rarity of the latter phenomena naturally excited universal interest, both among the astronomers and among the public. For the purpose in question it was necessary to send expeditions to different and distant parts of the globe, because the result had to depend upon the times of the phases, as seen from widely separated stations.

In 1869 the question what stations should be occupied and what observations should be made was becoming the subject of discussion in Europe, and especially in England. But our country was still silent on the subject. The result of continued silence was not hard to foresee. Congress would, at the last moment, make a munificent appropriation for sending out parties to observe the transit. The plans and instruments would be made in a hurry, and the parties packed off without any well-considered ideas of what they were to do; and the whole thing would end in failure so far as results of any great scientific value were concerned.

I commenced the discussion by a little paper on the subject in the "American Journal of Science," but there was no one to follow it up. So, at the spring meeting of the National Academy of Sciences, in 1870, I introduced a resolution for the appointment of a committee to consider the subject and report upon the observations which should be made. This resolution was adopted, and a few days afterward Professor Henry invited me to call at his office in the evening to discuss with himself and Professor Peirce, then superintendent of the Coast Survey, the composition of the committee.

At the conference I began by suggesting Professor Peirce himself for chairman. Naturally this met with no opposition; then I waited for the others to go on. But they seemed determined to throw the whole onus of the matter on me. This was the more embarrassing, because I believe that, in parliamentary law and custom, the mover of a resolution of this sort has a prescribed right to be chairman of the committee which he proposes shall be appointed. If not chairman, it would seem that he ought at any rate to be a member. But I was determined not to suggest myself in any way, so I went on and suggested Admiral Davis. This nomination was, of course, accepted without hesitation. Then I remarked that the statutes of the academy permitted of persons who were not members being invited to serve on a committee, and as the Naval Observatory would naturally take a leading part in such observations as were to be made, I suggested that its superintendent, Admiral Sands, should be invited to serve as a member of the committee. "There," said Peirce, "we now have three names. Committees of three are always the most efficient. Why go farther?"

I suggested that the committee should have on it some one practiced in astronomical observation, but he deemed this entirely unnecessary, and so the committee of three was formed. I did not deem it advisable to make any opposition at the time, because it was easy to foresee what the result would be.

During the summer nothing was heard of the committee, and in the autumn I made my first trip to Europe. On my return, in May, 1871, I found that the committee had never even held a meeting, and that it had been enlarged by the addition of a number of astronomers, among them myself. But, before it went seriously to work, it was superseded by another organization, to be described presently.

At that time astronomical photography was in its infancy. Enough had been done by Rutherfurd to show that it might be made a valuable adjunct to astronomical investigation. Might we not then photograph Venus on the sun's disk, and by measurements of the plates obtain the desired result, perhaps better than it could be obtained by any kind of eye observation? This question had already suggested itself to Professor Winlock, who, at the Cambridge Observatory, had designed an instrument for taking the photographs. It consisted of a fixed horizontal telescope, into which the rays of the sun were to be thrown by a reflector. This kind of an instrument had its origin in France, but it was first practically applied to photographing the sun in this country. As whatever observations were to be made would have to be done at governmental expense, an appropriation of two thousand dollars was obtained from Congress for the expense of some preliminary instruments and investigations.

Admiral Sands, superintendent of the observatory, now took an active part in the official preparations. It was suggested to him, on the part of the academy committee, that it would be well to join hands with other organizations, so as to have the whole affair carried on with unity and harmony. To this he assented. The result was a provision that these and all other preparations for observing the transit of Venus should be made under the direction of a commission to be composed of the superintendent of the Naval Observatory, the superintendent of the United States Coast Survey, the president of the National Academy of Sciences, and two professors of mathematics attached to the Naval Observatory. Under this provision the commission was constituted as follows: Commodore B. F. Sands, U. S. N., Professor Benjamin Peirce, Professor Joseph Henry, Professor Simon Newcomb, Professor William Harkness.

The academy committee now surrendered its functions to the commission, and the preparations were left entirely in the hands of the latter.

So far as scientific operations were concerned, the views of the commission were harmonious through the whole of their deliberations. It was agreed from the beginning that the photographic method offered the greatest promise of success. But how, with what sort of instruments, and on what plan, must the photographs be taken? Europeans had already begun to consider this question, and for the most part had decided on using photographic telescopes having no distinctive feature specially designed for the transit. In fact, one might almost say that the usual observations with the eye were to be made on the photograph instead of on the actual sun. The American commissioners were of opinion that this would lead to nothing but failure, and that some new system must be devised.

The result was a series of experiments and trials with Professor Winlock's instrument at the Cambridge Observatory. The outcome of the matter was the adoption of his plan, with three most important additions, which I shall mention, because they may possibly yet be adopted with success in other branches of exact astronomy if this telescope is used, as it seems likely it may be.

The first feature was that the photographic telescope should be mounted exactly in the meridian, and that its direction should be tested by having the transit instrument mounted in front of it, in the same line with it. In this way the axis of the telescope was a horizontal north and south line.

The next feature was that, immediately in front of the photographic plate, in fact as nearly in contact with it as possible without touching it, a plumb line of which the thread was a very fine silver wire should be suspended, the bob of which passed down below, and was immersed in a vessel of water to prevent vibration. In this way the direction of the north and south line on the plate admitted of being calculated with the greatest exactness, and the plumb line being photographed across the disk of the sun, the position angle could be measured with the same precision that any other measure could be made.

The third feature was that the distance between the photographic plate and the object glass of the telescope should be measured by a long iron rod which was kept in position above the line of sight of the telescope itself. This afforded the means of determining to what angle a given measure on the plate would correspond. The whole arrangement would enable the position of the centre of Venus with respect to the centre of the sun to be determined by purely geometric methods. One reason for relying entirely on this was that the diameter of the sun, as photographed, would be greater the greater the intensity of the photographic impression, so that no reliance could be placed upon its uniformity.

Ours were the only parties whose photographic apparatus was fitted up in this way. The French used a similar system, but without the essentials of the plumb line and the measurement of the length of the telescope. The English and Germans used ordinary telescopes for the purpose.

One of the earliest works of the commission was the preparation and publication of several papers, which were published under the general title, "Papers relating to the Transit of Venus in 1874." The first of these papers was a discussion of our proposed plan of photographing, in which the difficulties of the problem, and the best way of surmounting them, were set forth. The next, called