the field of cranio-cerebral topography we have frequently spoken. The accompanying table furnishes an idea of M. Topinard's classification:

CLASSIFICATION OF HUMAN RACES.

GEOGRAPHY AND TRAVELS.1

BRITISH ASSOCIATION. SIR WYVILLE THOMSON'S ADDRESS.— At the meeting held at Dublin this year, Sir Wyville Thomson on taking the chair of the Geographical Section began his address with a reference to the return of Mr. Stanley as one of the great events of the year 1877. He expressed admiration of the iron will and daring intrepidity which had successfully carried Mr. Stanley through his African exploration. Although in reading Mr. Stanley's narrative we may be forced to regret some of the dark scenes by which his terrible march was checkered, still no one who has not himself had some dealings with savages can fully understand how entirely the action of a leader, solely responsible for the lives of his party, must be guided in every emergency by considerations which he alone is in a position to weigh. The report, in eighteen volumes (after seventeen years' labor) of the circumnavigating voyage of the Austrian frigate Novara was another of the scientific events of the past year. He also referred to the voyage of the Italian corvette Magenta, the sounding voyages of Capt. Belknap in the Tuscarora, the Hassler expedition of the elder Agassiz, the tentative cruises of the British gunboats Lightning and Porcupine, culminating in the Challenger expedition, the expeditions to observe the transit of Venus, the several Swedish expeditions to the Spitzbergen sea, and the Arctic voyage of the Alert and Discovery, the account of which by Sir George Nares it was impossible to read without a feeling of regret that the devoted little band had attempted what was so 1 Edited by ELLIS II. YARNALL, Philadelphia.

hopeless, and at the same time a conviction that if their task had been practicable by human skill and bravery it must certainly have been accomplished. Speaking of the large contributions of Prof. Mohn and Prof. Sars, of Norway, to our knowledge of the distribution of temperature and the course of ocean currents, he remarked that Prof. Mohn spoke highly of the service rendered by Negretti and Zambra's new reversing thermometer, an instrument so constructed that by a simple mechanical arrangement the temperature might be registered at any given depth irrespective of any number of zones of temperature, higher or lower, through which the instrument may have passed in descending. In the Challenger the want of such a thermometer was greatly felt, for in the Arctic and Antarctic seas the coldest layer is frequently on the surface, and a warmer belt intervenes between it and a bottom stratum. At a depth averaging perhaps 500 fathoms we arrive at a temperature of 40° Fahr., and this may be regarded as a kind of neutral band separating the two layers. Above this band the temperature varies over different areas; beneath it the temperature almost universally sinks very slowly and with increasing slowness to a minimum at the bottom. Speaking generally, it may be said that the trade winds and their modifications and counter currents are the cause of all movements in the stratum above the neutral layer. One of the most singular results of late investigations is the establishment of the fact that all the vast mass of water, often upwards of 2,000 fathoms in thickness, below the neutral band is moving slowly to the northward, that, in fact, the depths of the Atlantic, the Pacific and the Indian oceans are occupied by tongues of the Antarctic sea, preserving in the main its characteristic temperatures. The immediate explanation of this very unexpected phenomenon seems simple. For some cause as yet not fully understood, evaporation is greatly in excess of precipitation over the northern portion of the land hemisphere, while over the water hemisphere, particularly its southern portion, the reverse is the case. Thus one part of the general circulation of the ocean is carried on through the atmosphere, the water being raised in vapor in the northern hemisphere is hurried by upper wind currents to the zone of low barometric pressure in the south, where it is precipitated in the form of snow or rain. Time would not allow him even to allude to the interesting results obtained from the determination of the density of sea water from different localities and depths. He must, however, say a few words as to certain additions which have been made to our knowledge of the regions round the North and South Poles. The question whether it is possible that there can be at all times or at any time anything in the form of an open Polar sea seems now to be virtually settled, and in the most unsatisfactory manner imaginable. From the observations of Count Wilczek in 1871 and Weyprecht and Payer in the follow

ing year, and from those of Dr. Hayes in 1861 and Capt. Nares in 1875-6, it is evident that the Polar basin is neither open sea nor continuous ice, but a fatal compromise between the two; and there seems now to be only two plans, one nearly as hopeless as the other, to choose between in any future attempt-either to establish permanent stations, as proposed by Lieut. Weyprecht and already initiated at one point by Capt. Tyson and Capt. Howgate, and to seize the opportunity of running north in early autumn from the station where the sea appears most open, or to run as far north as possible, at enormous expense, with a great force of men, and abundance of provisions, and paraffine oil, and push northwards during the Arctic winter by a chain of communicating stations, with ice-built refuge huts.

But little progress has been made during the past quarter of a century in the actual investigation of the conditions of the Antarctic regions. From information derived from all sources up to the present, it may be gathered that the unpenetrated area of 4,700,000 square miles surrounding the South Pole is by no means a continuous continent, but consists much more probably partly of comparatively low continental land, and partly of a series of continental islands bridged between and combined and covered to a depth of about 1,400 feet by a continuous ice cap. Several considerations appeared to him to be in favor of the view that the area round the South Pole is broken up and not continuous land. We have not only the presumed effect of the transfer of warmer water to the southwards, but in the Chailenger they had been able to detect its presence by the thermometer in high southern latitudes. It seems that all the icebergs are originally tabular, the surface being perfectly level and parallel with the surface of the sea, a cliff of about 230 feet high bounding the berg. It seems probable that under the enormous pressure to which the ice is subjected a constant system of melting is going on, the water passing down by gravitation from layer to layer until it reaches the floor of the ice sheet, and finally working out channels for itself between the ice and land. He could scarcely regret that it was utterly impossible for him on this occasion to enter into details with regard to the relations of the abyssal fauna. He must admit that the relations of the abyssal fauna to the fauna of the older tertiary and newer mesozoic periods, though much closer than those of the fauna of shallow water, were not so close as he had expected them to be; but he felt that until the zoological results of several later voyages, and especially those of the Challenger, should have been fully worked out, it would be premature to commit himself to any generalizations. Within the last decade the advance of knowledge bearing upon the physical geography of the sea has been confusingly rapid, so much so that at this moment accumulation of new material has far outstripped the power of combining, and digesting, and methodizing it. Steady progress is, however,

being made, and he trusted that in a few years our ideas as to the condition of the depths of the sea may be as definite as they are with regard to regions to which we have long had ready access. -London Times.

THE ARABIAN DESERT OF EGYPT.-Dr. G. Schweinfurth writes from Cairo, on the 18th of June, to the London Athenæum an account of his visit to the desert region lying between the Nile and the Red Sea. He started from a village near Atfih, on the Nile, on March 29th, and, taking a circuitous route, in the course of which he examined, more or less minutely, fifty-five wadis, returned to the Nile opposite to the town of Siut, on June 9th. Whilst he found remains of Roman settlements, neither inscriptions nor ruins indicate any knowledge of this region by the ancient Egyptians. The orographical and hydrographical features of this territory, to the east of the Nile, are far more varied than might have been expected. Every wadi has its own physiognomy. The rocks may belong to the same geological formation, but they vary exceedingly in contour and configuration. The wadis wind about in a curious manner, sloping down gently or steeply; the vegetation met within them is sometimes sporadic, at others ephemeral or continual; the animal world, too, contributes to impress a character upon each of the two hundred principal wadis which are met with in this small corner of Northeastern Africa.

MICROSCOPY.1

NATIONAL MICROSCOPICAL CONGRESS-This Convention, a call for which had been published by the Indianapolis Lyceum of Nat. Hist., assembled at Indianapolis on Wednesday morning, August 14th. About sixty members were in attendance, representing fifteen microscopical societies in different parts of the country. kev. A. B. Hervey was appointed chairman, and H. F. Atwood, secretary. Addresses of welcome were made by Mayor Caven and Dr. O. Evarts, and responded to by the chairman. Regular organization was then effected by the election of the following officers: President, Dr. R. H. Ward, of Troy; vice-presidents, Prof. J. E. Smith, of Cleveland, and Dr. W. W. Butterfield, of Indianapolis; secretary, H. F. Atwood, of Chicago; treasurer, Dr. J. B. Marvin, of Louisville. Four days were occupied with the meetings except Friday afternoon, which was devoted to a railway excursion. On Friday evening a soirée was given at the court house, which was largely attended by citizens. Owing to the large attendance and the limited number of instruments, no effort was made to classify the objects, and the exhibition was of altogether a popular character. On the last day of the meetings a special committee, which had been previously appointed, reported in favor of organizing permanently under the name of the "American Society of Microscopists," with a membership 1 This department is edited by Dr. R. H. WARD, Troy, N. Y.

open to all persons interested in microscopical science, and with meetings to be held annually at places selected during the previous meeting. After much discussion and no little difference of opinion as to radical points, the plan was adopted as reported, and Buffalo fixed upon as the place of meeting for next August. The following officers were unanimously elected for the first year: President, Dr. R. H. Ward, of Troy; vice-Presidents, S. W. Dennis, of San Francisco, and C. M. Vorce, of Cleveland; secretary, Dr. H. Jameson, of Indianapolis; treasurer, H. F. Atwood, of Chicago. The president-elect insisted upon declining election on the ground of having been presiding officer of the Congress, but finally withdrew his resignation. During the meeting papers were read on the following subjects, interesting discussions being drawn out by many of the papers:

"Limit of accuracy attainable in measurements with the microscope," by Prof. Wm. A. Rogers, of Cambridge. "Some new forms of mounting," by C. C. Merriman, of Rochester. Abstracts of these two papers will be published in a succeeding number.

"Formulæ of objectives," by W. H. Bulloch, of Chicago. The construction of several modern lenses of large immersion aperture was given in diagrams constructed from the lenses themselves, with results remarkably close to those formerly obtained by tracing the light mathematically through the objectives according to the data furnished by the makers.

"Angular aperture," by Dr. G. E. Blackham, of Dunkirk, N. Y. This paper gave a full review of the literature of the subject, limited angular aperture to the angular distance of the outside rays of the widest pencil of light, which the object glass could gather up and bring to a focus, with the formation of a well defined image of the object, and insisted upon the superiority, for all purposes, of well constructed objectives of extremely wide. angle.

46

Angular aperture defined," by Prof. Romyn Hitchcock, of New York. In order that the term angular aperture should mean something definite, and to avoid ambiguity and misunderstanding in future discussion on the subject, it was proposed to adopt a definition of the term which, right or wrong, should be recommended to the microscopists of the country as a convenient and uniform usage. The triangle method was proposed for general adoption, considering the angular aperture of a microscope objective to be the angle of the apex of a triangle having a base equal to the available diameter of the front lens, and a height equal to the actual focal length (working distance), measured in air for a dry lens, and in the fluid employed for an immersion, the collar being adjusted for the most perfect definition in every case. While nearly all the members seemed to be personally in favor of the usage proposed, a motion that the congress should attempt to settle the question by requesting its general adoption met with so much opposition that it was withdrawn.