Chapter 5

Consul Van Buren is of opinion that, at no distant day, Japan will be one of the foremost competitors in the pottery markets of the world, on account of the great variety and excellence of the clays, their proximity to the sea, the cheapness of labor, and the beauty and originality of the decorations. Already this important industry has been greatly stimulated by the foreign demand, and by the success of Japanese exhibitors at the Exhibitions of Vienna, Philadelphia, and Paris.--_Journal of the Society of Arts_.

* * * * *

Professor Julius E. Hilgard, for twenty years assistant in charge of the office, has been placed in temporary charge of the Coast and Geodetic Survey. It is understood that he will be appointed superintendent to succeed the late Captain Carlile P. Patterson.

* * * * *

THE FRENCH CRYSTAL PALACE.

The first idea of the French Crystal Palace was suggested by the English structure of the same name at Sydenham, about eight miles from London. Such a structure, as may be readily conceived, requires a site of vast extent, and one that shall be easy of access and possess the most agreeable surroundings. To the promoter of the project, those portions of the park of St. Cloud in the vicinage of the old chateau appeared to combine within themselves all the conditions that were desirable, and he, therefore, on the 15th of December, 1879, addressed the Ministers of Public Works and of Finances asking for the necessary concessions. The extensive specifications have been finally completed and will probably be shortly submitted for the approval of the parliament. The moment has arrived then for the public press to take cognizance of a project which concerns so great interests.

At present we shall say a few words _à propos_ of the engraving we present herewith. The French Crystal Palace will consist of one great nave, two lateral naves, two surrounding galleries, and a vast rotunda behind. The principal entrance, located at the head of the avenue leading from the present ruins (which will, ere long, be transformed into a most interesting museum), will exhibit a very striking aspect with its monumental fountain and the dome which it is proposed to erect over the very entrance itself. The whole structure will cover about nineteen acres of ground, thus being two and a half times the extent of the Palace of Industry in the Champs Elysees. The great nave of honor will be nearly 1,650 ft. in length, 78 ft. in width, and 98 ft. in height. The dome will measure exactly 328 ft. in height, or 105 ft. more than the towers of Notre Dame. The structure, with the exception of basement and foundation, will be of glass and iron.

The project which we publish to-day has been studied and gotten up, according to the general plans and dimensions suggested by the promoter, by Mr. Dumoulin, the architect. We are informed that the builder is to be Mr. Alfred Hunnebelle, a contractor well known from the extensive works that he has executed, and who is president of the Syndical Chamber of Contractors of Paris.

Among the annexes of this palace we may note a "Palace of the Republic," to be built on the ruins and designed for illustrious or distinguished visitors, such as the President of the Republic, the Ministers, the Municipal Council of Paris, foreign delegates, etc.; a farm house for special exhibitions and a field for experiments; galleries, cottages, etc.

As for the programme, which embraces six divisions and numerous subdivisions, we are unable to give it at present for want of space; we need only say that it satisfies perfectly all the conditions of so vast an undertaking.

In the hands of the projector, Mr. Nicole, who is well known from his long experience in such matters, the exhibition will undoubtedly prove a success and be instrumental in adding prosperity to all French industries.

* * * * *

THE GREAT HEAT OF THE SUN.--Prof. S. P. Langley has made the following calculation: A sunbeam one centimeter in section is found in the clear sky of the Alleghany Mountains to bring to the earth in one minute enough heat to warm one gramme of water by 1° C. It would, therefore, if concentrated upon a film of water 1/500th of a millimeter thick, 1 millimeter wide, and 10 millimeters long, raise it 83 1/3° in one second, provided all the heat could be maintained. And since the specific heat of platinum is only 0.0032 a strip of platinum of the same dimensions would, on a similar supposition, be warmed _in one second_ to 2,603° C.--a temperature sufficient to melt it!

* * * * *

CHATEAU IN THE AEGEAN SEA.

From the site of this building, magnificent views are obtained over the island-dotted sea and the mainland of Asia Minor: but, "though every prospect pleases," it is a land of earthquakes, and unfortunately, the works at the chateau have been suspended, owing to the dreadful calamity which has recently fallen upon the district. The building is intended for the residence of an English lady of exalted rank. It is to be built of local white stone, the hall, staircase, etc., being lined and paved with marbles. The hall is a large apartment about 25 ft. high, with paneled ceiling, having galleries on two sides, giving access to the rooms surrounding it on first floor, and to the turret staircase leading to roofs, etc. With the exception of sanitary apparatus, painted windows, etc. (which will be supplied by English firms), the whole of the work will be executed by native labor. The architect is Mr. Edwin T. Hall, London.--_Building News_.

* * * * *

ELECTRIC POWER.

Just now nothing save electricity is talked about in scientific circles. During the meeting of the British Association the greatest possible prominence was given to electrical questions and propositions The success of the electric light, the introduction of the Faure battery with a great flourish of trumpets, and the magnificent display of electrical instruments and machinery at Paris, have all operated to the same end. The daily press has taken the subject up, and journals which were nothing hitherto if not political, now indulge in magnificent rhapsodies concerning the future of electricity. Even eminent engineers, carried away by the intoxication of the moment, have not hesitated to say that the steam engine is doomed, and that its place will be taken by the electricity engine. In the midst of all this noise and clamor and blowing of personal trumpets, it is not easy to keep one's head clear, and mistakes may be made which will cause disappointment to many and retard the progress of electrical science. We confidently expect that electricity will prove a potent agent by and by in the hands of the speculator for extracting gold from the pockets of the public, and we write now to warn our readers in time, and to endeavor to clear the air of some of the mists with which it is obscured. There is, no doubt, a great future before electricity; but it is equally certain that electricity can never do many things which the half informed may be readily made to believe it will do. We propose here to say enough on this point to enlighten our readers, without troubling them with perplexing problems and speculations.

No one at this moment knows what electricity is; but for our present purpose we may regard it as a fluid, non-elastic, and without weight, and universally diffused through the universe. To judge by recently published statements, a large section of the reading public are taught that this fluid is a source of power, and that it may be made to do the work of coal. This is a delusion. So long as electricity remains in what we may call a normal state of repose, it is inert. Before _we can get any work out of electricity a somewhat greater amount of work must be done upon it_. If this fundamental and most important truth be kept in view it will not be easy to make a grave mistake in estimating the value of any of the numerous schemes for making electricity do work which will ere long be brought before the public. To render our meaning clearer, we may explain that in producing the electric light, for instance, a certain quantity of electricity passes in through one wire to the lamp, and precisely the same quantity passes out through the other wire, and on to the earth or return wire completing the circuit. Not only is the quantity the same, the velocity is also unchanged. But in going through the lamp the current has done something. It has overcome the resistance of the carbons, heated them to a dazzling white heat, and so performed work. In doing this the current of electricity has lost something. Led from the first lamp to a second, it is found powerless--if the first lamp be of sufficient size. What is it that the electricity has lost? It has parted with what electricians would term "potential," or the capacity for performing work. What this is precisely, or in what way the presence or absence of potential modifies the nature of the electric current, no one knows; but it is known that this potential can only be conferred on electricity by doing work on the electricity in the first instance. The analogy between electricity and a liquid like water will now be recognized. So long as the water is at rest, it is inert. If we pump it up to a height, we confer on it the equivalent of potential. We can let the water fall into the buckets of an overshot wheel. Its velocity leaving the tail race may be identical with that at which it left the supply trough to descend on the wheel. Its quantity will be the same. It will be in all respects unchanged, just as the current of electricity passing through a lamp is unchanged; but it has, nevertheless, lost something. It has parted with its potential--capacity for doing work--and it becomes once more inert. But the duty which it discharged in turning the mill wheel was somewhat less than the precise equivalent of the work done in pumping it up to a level with the top of the wheel. In the same way the electric current never can do work equal in amount to the work done on it in endowing it with potential.

It will thus be seen that electricity can only be used as a means of transmitting power from one place to another, or for storing power up at one time to be used at a subsequent period; but it cannot be used to originate power in the way coal can be used. It possesses no inherent potential. It is incapable of performing work unless something is done to it first. We have spoken of it as a fluid, but only for the sake of illustration. As we have said, no one knows what it is, but the theory which bids fair for acceptance is that it is a mode of motion of the all-pervading ether. Very curious and instructive experiments are now being carried out in Paris by Dr. Bjerkness, of Christiania, in the Norwegian section of the electrical exhibition. This gentleman submerges thin elastic diaphragms in water, and causes them to vibrate, or rather pulsate, by compressed air. He finds that if they pulsate synchronously they attract each other. If the pulsations are not simultaneous, the disks repel each other. From this and other results he has obtained, it may be argued that the ether plays the part of the water in Dr. Bjerkness' tank, and that when special forms of vibration are set up in bodies they become competent to attract or repel other bodies. This being so, it will be seen that the power of attraction or repulsion of an electrical body depends in the first instance on the motion set up in the body attracted or repulsed, and this motion is, of course, some function of the work originally done on the body. We need not pursue this argument further. Among the most scientific investigators of the day it is admitted that the efficiency of electricity as a doer of work, or a producer of action at a distance, must depend for its value on the performance of work in some one way or another on the electricity itself in the first instance. It may be worth while here to dispel a popular delusion. It is held very generally that electricity can be made, as, for instance, by the galvanic battery. There is no reason to believe anything of the kind; but whether it is or is not true that electricity is actually made by the combustion of zinc in a galvanic trough, it is quite certain that this electricity, unless it possesses potential, can do no work, no matter how great its quantity. Of course, it is to be understood that all electric currents possess potential. If they did not, their presence would be unknown; but the potential of a current is in all cases the result of work done on electricity, either by the oxidation of zinc, or in some other way. This is a broad principle, but it is strictly consistent in every respect with the truth. Electricity, then, is, as we have said, totally different from coal; and it can never become a substitute for it alone. Water power, air power, or what we may, for want of a better phrase, call chemical power, combined with electricity, can be used as a substitute for coal; but electricity cannot of itself be employed to do work. It is true, however, that electricity, on which work has already been done, may be found in nature. Atmospheric electricity, for example, may perhaps yet be utilized. It is by no means inconceivable that the electricity contained in a thunder cloud might be employed to charge a Faure battery; but up to the present no one has contemplated the obtaining of power from the clouds, and whether it is or is not practicable to utilize a great natural force in this way does not affect our statement. The use of electricity must be confined to its power of transmitting or storing up energy, and this truth being recognized, it becomes easy to estimate the future prospects of electricity at something like their proper value.

It has been proved to a certain extent that electricity can be used to transmit power to a distance, and that it can be used to store it up. Thus far the man of pure science. The engineer now comes on the stage and asks--Can practical difficulties be got over? Can it be made to pay? In trying to answer these questions we cannot do better than deal with one or two definite proposals which have been recently made. That with which we shall first concern ourselves is that trains should be worked by Faure batteries instead of by steam. It is suggested that each carriage of a train should be provided with a dynamo motor, and that batteries enough should be carried by each to drive the wheels, and so propel the train. Let us see how such a scheme would comply with working conditions. Let us take for example a train of fifteen coaches on the Great Northern Railway, running without a stop to Peterborough in one hour and forty minutes. The power required would be about 500 horses indicated. To supply this for 100 minutes, even on the most absurdly favorable hypothesis, no less than 25 tons of Faure batteries would be required. Adding to these the weight of the dynamo motors, and that unavoidably added to the coaches, it will be seen that a weight equal to that of an engine would soon be reached. The only possible saving would be some 28 to 30 tons of tender. In return for this all the passengers would have to change coaches at Peterborough, as the train could not be delayed to replace the expended with fresh batteries. This is out of the question. The Faure batteries must all be carried on one vehicle or engine, which could be changed for another, like a locomotive. Even then no advantage would be gained. As to cost, it is very unlikely that the stationary engines which must be provided to drive the dynamo machines for charging the batteries would be more economical than locomotive engines; and if we allow that the dynamo machine only wasted 10 per cent. of the power of the engine, the Faure batteries 10 per cent. of the power of the dynamo machines, and the dynamo motors 10 per cent. of the power of the batteries--all ridiculously favorable assumptions--yet the stationary engines would be handicapped with a difference in net efficiency between themselves and the locomotive--admitting the original efficiency per pound of coal in both to be the same--of some 27 per cent., we think we may relegate this scheme to the realms of oblivion. Another idea is that by putting up turbines and dynamo machines the steam engine might be superseded by water power. Now it so happens that if all the water power of England were quadrupled it would not nearly suffice for our wants. It may be found worth while perhaps to construct steam engines close to coalpits and send out power from these engines by wire; but the question will be asked, Which is the cheaper of the two, to send the coal or to send the power? On the answer to this will depend the decision of the mill owners. Another favorite scheme is that embodied in the Siemens electrical railway. We believe that there is a great future in store for electricity as a worker of tramway traffic; but the traffic on a great line like the Midland or Great Northern Railway could not be carried on by it. As Robert Stephenson said of the atmospheric system, it is not flexible enough. The working of points and crossings, and the shunting of trains and wagons, would present unsurmountable difficulties. We have cited proposals enough, we think, to illustrate our meaning. Sir William Armstrong, Sir Frederick Bramwell, Dr. Siemens, Sir W. Thomson, and many others may be excused if they are a little enthusiastic. They are just now overjoyed with success attained; but when the time comes for sober reflection they will, no doubt, see good reason to moderate their views. No one can say, of course, what further discoveries may bring to light; but recent speakers and writers have found in what is known already, materials for sketching out a romance of electricity. It is but romancing to assert that the end of the steam engine is at hand. Wonderful and mystical as electricity is, there are some very hard and dry facts about it, and these facts are all opposed to the theory that it can become man's servant of all work. Ariel-like, electricity may put a girdle round the earth in forty minutes; but it shows no great aptitude for superseding the useful old giant steam, who has toiled for the world so long and to such good purpose--_The Engineer_.

* * * * *

ON A METHOD OF OBTAINING AND MEASURING VERY HIGH VACUA WITH A MODIFIED FORM OF SPRENGEL-PUMP.

By Ogden N. Rood, Professor of Physics in Columbia College.

In the July number of this Journal for 1880, I gave a short account of certain changes in the Sprengel-pump by means of which far better vacua could be obtained than had been previously possible. For example, the highest vacuum at that time known had been reached by Mr. Crookes, and was about 1/17,000,000, while with my arrangement vacua of 1/100,000,000 were easily reached. In a notice that appeared in _Nature_ for August, 1880, p. 375, it was stated that my improvements were not new, but had already been made in England four years previously. I have been unable to obtain a printed account of the English improvements, and am willing to assume that they are identical with my own; but on the other hand, as for four years no particular result seems to have followed their introduction in England, I am reluctantly forced to the conclusion that their inventor and his customers, for that period of time, have remained quite in ignorance of the proper mode of utilizing them. Since then I have pushed the matter still farther, and have succeeded in obtaining with my apparatus vacua as high as 1/390,000,000 without finding that the limit of its action had been reached. The pump is simple in construction, inexpensive, and, as I have proved by a large number of experiments, certain in action and easy of use; stopcocks and grease are dispensed with, and when the presence of a stopcock is really desirable its place is supplied by a movable column of mercury.

_Reservoir_.--An ordinary inverted bell-glass with a diameter of 100 mm. and a total height of 205 mm. forms the reservoir; its mouth is closed by a well-fitting cork through which passes the glass tube that forms one termination of the pump. The cork around tube and up to the edge of the former is painted with a flexible cement. The tube projects 40 mm. into the mercury and passes through a little watch-glass-shaped piece of sheet-iron, W, figure 1, which prevents the small air bubbles that creep upward along the tube from reaching its open end; the little cup is firmly cemented in its place. The flow of the mercury is regulated by the steel rod and cylinder, CR, Figure 1. The bottom of the steel cylinder is filled out with a circular piece of pure India-rubber, properly cemented; this soon fits itself to the use required and answers admirably. The pressure of the cylinder on the end of the tube is regulated by the lever, S, Figure 1; this is attached to a circular board which again is firmly fastened over the open end of the bell-glass. It will be noticed that on turning the milled head, S, the motion of the steel cylinder is not directly vertical, but that it tends to describe a circle with c as a center; the necessary play of the cylinder is, however, so small, that practically the experimenter does not become aware of this theoretical defect, so that the arrangement really gives entire satisfaction, and after it has been in use for a few days accurately controls the flow of the mercury. The glass cylinder is held in position, but not supported, by two wooden _adjustable_ clamps, _a a_, Figure 2. The weight of the cylinder and mercury is supported by a shelf, S, Figure 2, on which rests the cork of the cylinder; in this way all danger of a very disagreeable accident is avoided.

_Vacuum-bulb_.--Leaving the reservoir, the mercury enters the vacuum-bulb, B, Figure 2, where it parts with most of its air and moisture; this bulb also serves to catch the air that creeps into the pump from the reservoir, even when there is no flow of mercury; its diameter is 27 mm. The shape and inclination of the tube attached to this bulb is by no means a matter of indifference; accordingly Figure 3 is a separate drawing of it; the tube should be so bent that a horizontal line drawn from the proper level of the mercury in the bulb passes through the point, _o_, where the drops of mercury break off. The length of the tube, EC, should be 150 mm., that of the tube, ED, 45 mm.; the bore of this tube is about the same as that of the fall-tube.