Part 17

=Wave Length and other Measurements.=--Describing the measurement of absolute wave length before the Astronomical and Physical Society of Toronto, Mr. A. F. Miller remarked that a somewhat incorrect idea prevailed as to the smallness of the space occupied in the performance of luminous undulations; in fact, some people seem to regard the wave length of light as something almost inconceivably small. Really, however, we are familiar with much smaller dimensions. For instance, the author had found from actual measures that the wave length of one of the characteristic lines in the spectrum of sodium vapor was very nearly equal to 1/42000 of an inch. The thickness of ordinary gold leaf is given as 1/282000 of an inch, from which it becomes evident that the wave length of sodium light, which is an average wave length for the visible spectrum, is six and a half times as great as the thickness of gold leaf. Such a dimension as 1/42000 of an inch could readily be measured by a suitable micrometer; but of course the waves of light, as well as the ether particles by which they are transmitted, are entirely invisible, and even were this otherwise the frequency of the undulations is so inconceivably great that the actual phenomena of the movements could never become perceptible. In measuring the absolute wave length, therefore, we are forced to take the indirect method of observing the results of undulations in cases where, by a suitable arrangement of the experiment, equal and opposite phases of vibration are made to arrive simultaneously at the same spot, so producing phenomena of interference.

=The "Causses" of Southern France.=--It is surprising to find existing, in a country so old and supposedly so familiar as France, a region similar to our Colorado plateau, full of cañons, caves, and cliff dwellings, until recently almost unknown and wholly unexplored. Yet such is the region of the Causses, described and illustrated with a striking series of lantern views, before the American Association for the Advancement of Science, by the well-known cave explorer, Dr. H. C. Hovey, of Newburyport, Mass. The local name Causse, derived from the Latin calx, lime, is applied to a limestone area, and here to a limestone plateau. Along the western slope of the Cévennes Mountains lies an elevated table-land, chiefly of Jurassic limestones, which had been cut and carved by the streams, especially the Tarn and its affluents, into a group of high plateaus separated by deep cañons. The cliffs of the Tarn Valley are from one to two thousand feet and even more in height, and with their precipitous sides and the brilliant and varied coloring of their strata are not unworthy of comparison with our own great cañon regions of the West. At some points, where the beds are markedly unequal in hardness, the weathering process has resulted in structures as remarkable as Monument Park or the Garden of the Gods. Such is the "rock city" known as Montpellier-le-Vieux, at the junction of the Jonté and the Durbais, on the Causse Noir. This strange area of natural ruins covers some two thousand acres with a fantastic similitude of castles, palaces, streets, and temples. It seems surprising that a country so picturesque for the tourist and so interesting for the geologist should have remained almost unknown till the present time. Fine roads pass over and around it, but they avoid the wild and rugged portions that possess such scenic interest, and leave the Causses--as they have been for ages--barren solitudes, occupied only by shepherds with their huts and flocks. The people, also, as is so often the case in such regions, have a superstitious dread of the deeper caverns and the seeming ruins, and do not lend themselves readily to exploration. The cliffs are full of caves, some of which--the more accessible and simple--are used as sheepfolds, and even in some cases inhabited, but the wilder ones are held in dread. It seems that cliff dwellings are actually still in use to some extent in this region. The French Société de Spéléologie has now for some years been investigating the Causses with great interest. Ere long this will become a favorite region for tourists; but at present one must leave all ordinary facilities of travel and take to canoes and mules. This was done by Dr. Hovey and his party, under the leadership of M. Edouard A. Martel, of Paris, who has been one of the most active explorers. They entered and traversed many remarkable caves, some never before visited, and some that have been previously explored by M. Martel and others of the société. One of these, known as the Baumes Chaudes, is a great triple cavern, one of the main branches of which had yielded a large number of prehistoric skeletons to Dr. Prunières, of Marvejol. In the third division are a number of deep pits, locally called "wells," from forty to a hundred and thirty feet deep; these communicate with lower passages and subterranean streams. They are death-traps to animals, the remains of which, of many kinds and in all stages of decomposition, accumulate at the bottom, and are gradually covered by stalagmitic deposits. Another remarkable cave was discovered and named after its daring and enthusiastic explorer, M. Louis Armand, of Paris. It can only be entered by a "well" two hundred and forty feet deep, and below this lies another of still greater depth. The party was provided with rope ladders for use in such places; and the intrepid investigator who essayed the descent went down, by actual measurement, six hundred feet from the surface. He described the stalactites as magnificent. Both from a geological and an archæological point of view this account was of unusual interest. Dr. Hovey had many beautiful views of the cañons and the cave openings in their walls; while his observations, and those of the Société de Spéléologie, are very curious as to the persistence, in this strangely overlooked region, of conditions closely akin to what are usually called "prehistoric" times.

=Molecular Asymmetry and Life.=--Speaking in his presidential address to the Chemical Section of the British Association on Stereochemistry and Vitalism, Prof. A. R. Japp expressed the conclusion that "the production of single asymmetric compounds or their isolation from the mixture of their enantiomorphs [or opposite forms] is, as Pasteur firmly held, the prerogative of life. Only the living organism, with its asymmetric tissues, or the asymmetric productions of the living organism, or the living intelligence with its conception of asymmetry, can produce this result. Only asymmetry can beget asymmetry. The absolute origin of the compounds of one-sided asymmetry is a mystery as profound as the absolute origin of life itself. The two phenomena are intimately connected.... No fortuitous concourse of atoms, even with all eternity for them to clash and combine in, could compass this feat of the formation of the first optically active organic compound. Coincidence is excluded, and every purely mechanical explanation of the phenomena must necessarily fail. I see no escape from the conclusion that at the moment when life first arose a directive force came into play--a force of precisely the same character as that which enables the intelligent operator, by the exercise of his will, to select one crystallized enantiomorph and reject its asymmetric opposite. I would emphasize the fact that the operation of a directive force of this nature does not involve a violation of the law of the conservation of energy."

=Dr. Russell's Photographic Researches.=--At the recent meeting of the British Association at Bristol, Dr. W. T. Russell gave, before the Chemical Section, some further information regarding his recent researches on the surprising action exerted by certain substances in the absence of light on photographic plates. The Journal of the Society of Arts gives some of his more striking results: "Some ordinary type, a portion of the cover of Punch, and the wrapper of a packet of tobacco produced strongly defined pictures; the last mentioned was particularly interesting, inasmuch as the red ink had proved active, the blue inactive. Strangely, writing ink (old-fashioned) is quite inactive, and paper having writing on it in ink, even over a hundred years old, when placed between a sheet of active material and a sensitive plate, yielded a picture in which the writing appeared quite distinctly, white on black, in spite of the original being in some cases indistinct; ferrous sulphate behaves like ink. The list of materials that are active is very long, and includes wood, which gives a picture of the grain and knots. Many metals are active, but zinc is very active only when bright, so that a dirty sheet of zinc rubbed with sandpaper gives a picture of the scratches. Many alloys are also active, pewter and fusible metal being two of them, and curiously some brasses are, while others are not. The effective agency that passes from the material to the sensitive plate shows peculiarities. It passes through gelatin, gutta-percha, celluloid, collodion, wet gum arabic, and some paper, while other paper, glass, minerals transparent to light, and many other substances are opaque to these emanations, and some striking effects were exhibited demonstrating the interference of these opaque substances when interposed between an active substance and the sensitive plate. For instance, a five-pound note placed printing downward on the sensitive plate gave a picture of the printing inscription, but when placed under a zinc plate with the printing toward the zinc plate it gave a picture of the opaque paper with the water marks distinctly showing, and, what is still more astonishing, the zinc plate, after contact with the note, itself yielded a picture of the inscription, showing that the influence from the ink had passed to the zinc plate. It was noteworthy that the signature was not in writing ink. A cutting from the Times, the paper being transparent, showed a picture of the printing on both sides; the picture, moreover, was reversible, showing that a perfect picture of both sides of the paper had been impressed on the one plate. This interesting phenomenon is, however, not quite explained, but the great amount of work he has done leads him to the provisional opinion that the effect is due to the evolution of hydrogen peroxide."

=Scientific "Trade Hunting."=--The recent movement in England toward the establishment by the Government of a commercial intelligence office for the securing and diffusion of information regarding foreign trade has given rise to considerable discussion among the English trade papers. The business of the office is to be the gathering of general information of interest and value to the English merchant with a foreign trade, and especially of pointing out new ways for the extension of foreign commerce, and calling attention to possible new markets for English goods. A number of schemes have been proposed, among others that of sending an expert once every year or two to the different foreign "trade areas," for the purpose of collecting information and samples, and of giving a trustworthy estimate of its commercial prospects; another, that of extending the consular reports in such a manner as to compass the same ends. There is considerable opposition to the scheme from some branches of business, where it is held that no one is so likely to get hold of useful information as the trader himself, and that the publishing of such Government reports as the scheme contemplates would result in giving the information to foreign as well as English traders, and thus negative whatever advantage might come to the English merchant from his individual discovery of a valuable market.

=Dr. Neufeld.=--The London Times of September 13th gives the following account of the career of Dr. Neufeld, who has just been delivered from captivity in Omdurman by the English forces: "Karl Neufeld studied medicine at Leipsic University, and went early in life to Egypt, following first his profession as a medical man and subsequently as a merchant. At the beginning of the eighties he had a practice at Keneh, Upper Egypt, where several Germans and also natives of his own home saw him. Subsequently he set up as a merchant at Assouan. After the fall of Khartoum and the firm establishment of the Mahdi's power at Omdurman, Neufeld seems to have formed a scheme for opening up commercial intercourse with the closed Soudan, for he equipped a caravan with which he proceeded to Berber, which was then in the hands of Osman Digna. The latter sent the German, whom he looked upon as a dangerous spy, to the Khalifa Abdullahi. This was in 1886. Neufeld was condemned to death, and was taken to the place of execution. He behaved there so courageously, asking to be executed like a Mohammedan, instead of suffering death by hanging, that the Khalifa was struck and respited him under the gallows. He was taken to the general prison, with heavy chains on his hands and feet, and treated altogether in a most abominable manner. He was kept alive by the women, who took pity on him and fed him, as they had done before him to Slatin. Then an endeavor was made to utilize his knowledge. He knew nothing about founding cannon, but he managed to manufacture powder, and he was also ordered to invent a machine for coining money. Owing to the escape of Father Ohrwalder and, later, of Slatin Pasha, his position became worse. He was again manacled and threatened with having his arms and feet hacked off if he should attempt to escape. There were many efforts to liberate him. The Austrian Catholic mission, induced by Father Ohrwalder, Slatin Pasha, the British Government, the German, and more especially the Austrian, representatives at Cairo, all endeavored to further the escape of Neufeld. He frequently received money, but he refused to escape, as he would not accept liberty without his wife--an Abyssinian slave presented to him by the Khalifa--and the two children whom she had borne him. The latter would have been exposed to fearful tortures, and thus Neufeld chose to remain a prisoner. He was active subsequently also as an artist, and as he could draw well he was ordered to decorate the mausoleum of the Mahdi, and this pleased the women of the Khalifa so much that they petitioned the latter for his liberation. It is also said that he has written Arabic books and illustrated them. The latter part of his twelve years' detention appears to have been less onerous, as after the escape of Slatin he had to be interpreter to the Khalifa and translator of European newspapers which the ruler of the Soudan received regularly. It is to the credit of the Khalifa Abdullahi that not one of the Christian prisoners received a hurt on the approach of the Anglo-Egyptian forces. It is expected that a narrative of his experience in the Soudan will be shortly published by Dr. Neufeld."

=Natural Selection and Fortuitous Variation.=--The three principal objections urged against Darwin's theory of natural selection were stated by Prof. W. F. R. Weldon, in his presidential address to the Section of Zoology and Physiology of the British Association, as being that the species of animals we know fall into orderly series for the selection of which purely fortuitous variations can not be supposed to afford opportunity; that minute structural variations can not be supposed to affect the death-rate so much as the theory requires they should, while many of the characters by which species are distinguished appear to us so small and useless that they can not be supposed to affect the chance of survival at all; and that the process of evolution by natural selection is so extremely slow that the time required for its operation is longer than the extreme limit of time given by estimates of the age of the earth. The first of these objections the speaker alleged to be due to a misunderstanding of words; we regard as fortuitous what we do not understand; and he proceeded to explain how what we call chance may be shown, especially by a method developed by Professor Pearson, to be a real and important factor. To the other two objections Professor Weldon opposed the results of observations of his own and of Mr. Herbert Thompson on the small shore crabs (_Carcinus mœnas_) at Plymouth Beach. "In these crabs small changes in the size of the frontal breadth do, under certain circumstances, affect the death-rate; and the mean frontal breadth among this race of crabs is, in fact, changing at a rate sufficiently rapid for all the requirements of a theory of evolution." In conclusion, he said: "I hope I have convinced you that the law of chance enables one to express easily and simply the frequency of variations among animals, and I hope I have convinced you that the action of natural selection upon such fortuitous variations can be experimentally measured, at least in the only case in which any one has attempted to measure it. I hope I have convinced you that the process of evolution is sometimes so rapid that it can be observed in the space of a very few years." The whole difficulty of natural selection, he added, is a quantitative difficulty; and he insisted upon the need of observations and measurements of the rates of variation.

=The Interior of Canada.=--The country between Lake St. John and James Bay is under survey by the Department of Colonization and Mines of Quebec, in furtherance of a scheme for a transcontinental railroad to tap the Hudson Bay country and Lake Winnipeg. As to the commercial advantages of a railway center established at the head of James Bay or at the limit of tide water on the Nottaway River, Mr. O'Sullivan, the surveyor, shows that the shore line of Hudson and James Bay, following the east coast from the mouth of the Nottaway to the southern entrance to Hudson Strait, measures, in a line running due north, eight hundred miles, or about the same distance as the former point is north of the city of Washington; and the western shore line, measured in the same way to Rowe's Welcome, is about sixteen hundred miles, while the area inclosed amounts to more than three hundred and fifty thousand square miles. While Hudson Strait is blocked with ice during nine months of the year, the bay itself is navigable from June till November, and James Bay is generally open early in May. All the large rivers--the Albany, Moose, Hannah, Nottaway, Rupert, Main, and Big Rivers--converge along these shores, and the forest wealth of the thousands of miles drained by these and lesser rivers can be concentrated at the mouth of the Nottaway or Rupert. The land along the line from Lake St. John is good dry land fit for settlement. The Nottaway at the crossing point is fourteen hundred and fifty feet wide, and admits bridge spans of five hundred feet. Thence, a direct line to Norway House, at the foot of Lake Winnipeg, would pass through the gypsum beds on Moose River, and give access to a vast area of rich agricultural land in the north part of the province of Quebec. The straight line continued would strike about the forks of the Peace and Smoky Rivers, near the center of the northwest wheat-growing region, and thence follow the valleys of the Peace and Skeene Rivers to the Pacific Ocean, crossing the Rocky Mountains at a point where the summit is two thousand feet lower than that of the Canadian Pacific Railway. As to the resources of this northwestern country, there are, according to a Dominion official report, an area of six hundred and fifty-six thousand square miles along the Mackenzie River suitable for the growth of potatoes, four hundred and seven thousand suitable for barley, and three hundred and sixteen thousand for wheat, with a pastoral area of eight hundred and sixty thousand square miles, two hundred and seventy-four thousand miles of which may be regarded as arable land. "The difference in latitude makes no corresponding difference in the climate. Flowers bloom as early in the spring and as late in autumn at Great Slave Lake as at Winnipeg or St. Paul and Minneapolis. The prevailing southwest or Chinook winds render the climate along the Peace and Liard Rivers as mild and salubrious as that of western Ontario. Wheat ripens along the Mackenzie River under the Arctic Circle, a thousand miles farther north than Rupert House."

MINOR PARAGRAPHS.

MR. W. H. HUDDLESTON, in his presidential address to the Geological Section of the British Association, spoke of the geology of the southwest of England, and began with supporting the claim of Bristol, where the association was meeting, to be regarded as the cradle of British geology, and even more; for, he said, Devonshire, Cornwall, and West Somerset first attracted the attention of the Ordnance Geological Survey. "Thus it comes to pass that the region which lies between the Bristol Channel and the English Channel claims the respect of geologists in all parts of the world, not only as the birthplace of stratigraphical paleontology, but also as the original home of systematic geological survey. The city of Bristol lies on the confines of this region, where it shades off northwestward into the Palæozoics of Wales and northeastward into the Mesozoics of the midland counties."

A COMMITTEE of the English Society of Arts, appointed to inquire into the matter, attribute the doubtful quality of modern paper to "revolutionary" changes which the industry has undergone, including the introduction of new substances of varying qualities and chemical properties, in the working up of which there is still room for much improvement. The committee have examined many books, as evidence, on the question of the deterioration of paper. They distinguish two tendencies--to disintegration and to discoloration--which are independent but may be concurrent effects, and are notably concurrent in papers containing mechanical wood pulp. Disintegration, which has been brought to light in papers of all grades, is generally the result of chemical changes in the fibers, produced by acids in the rag papers, and by oxidation in the papers made of mechanical wood pulp. Discoloration of ordinary cellulose papers, as distinguished from papers containing mechanical wood pulp, is dependent upon the quality of the sizing, and particularly the proportion of rosin in it. The committee define as the normal standard of quality for book papers, required for publications of permanent value, fibers not less than seventy per cent of the cotton, flax, and hemp class, sizing not more than two per cent rosin, the paper to be finished with the normal acidity of pure alum, and the loading to be not more than ten per cent mineral matter.

COLONEL G. E. CHURCH, president of the Geographical Section of the British Association, pointed out in his opening address, which was on Argentine geography and the ancient Pampean Sea, that the drainage area of the Plata basin was, according to Dr. Bludan, 1,198,000 square miles, or more than two and a half times that of the Pacific slope of the Andes. The minimum water discharge into the Plata estuary would, every twenty-four hours, make a lake one mile square and 1,650 feet deep. About seventy-four per cent of it would represent the flow of the Paraná, and twenty-six per cent that of the Uruguay River. These interlaced with the affluents of the Amazon along a line of fourteen degrees of longitude. The author sought to show that the Plata drainage area was, in a recent geological period, much more extensive than it is to-day; that its extreme northern limit was in 10° 44' south latitude, and that nearly all the waters that now unite to form the Madeira River, the main affluent of the Amazon, once flowed southward into a Pampean sea that penetrated north over the plains of the present Argentine Republic to about 19° south latitude.