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falling. Now, if we assume that the region around Stone Mountain is undergoing a very gradual elevation or depression, then it will follow that the rocky strata will be brought into a condition of stretching or tension which will go on until the limit of elastic cohesion is reached, when a rupture or crack will suddenly take place which must be attended with a jar, and, in some cases, with an audible sound. If the rocky strata is of the same material from the surface down into the interior; for example, granite, and the mountain being in the process of depression, the crack will take place deep in the interior. If, on the other hand, the mountain is being elevated, the crack will be at the surface. If, however, the upper strata are more extensible than the deeper seated, the crack may be in the interior in the case of an elevation as well as in that of a depression.

It has of late years been suspected, from the discrepancy in later and older measurements of points on the Andes, that this mountain system is in a state of very slow subsidence.

If the foregoing views are correct there is no indication of a volcanic outburst; and whatever moral effect the disturbances may have on the character of the inhabitants of the region, there is little danger as to any physical changes taking place of sufficient intensity to endanger life.-J. H.]

REPORT ON THE TRANSACTIONS OF THE SOCIETY OF PHYSICS AND NATURAL HISTORY, OF GENEVA, FROM JUNE, 1872, TO JUNE, 1873.

BY PROF. A. DE LA RIVe, President.

[Translated for the Smithsonian Institution.]

GENTLEMEN: Called a second time, through your kindness, to preside over you, again I have the honor to present the annual report of such of your transactions as your president has considered it desirable to register. Happily, this year, that part of the report appropriated to biographical notices is extremely brief. The society, after the great losses it sustained during last year, has not this year been called to mourn a single one of its ordinary regular members. But of its honorary members two have been taken away, Madame Somerville and Arnold Escher de la Linth. I have little to say of Madame Somerville, who has made for herself a brilliant reputation, during the last fifty years, by her mathematical works, and especially by her translation into English of the Mécanique céleste of Laplace. She was in full sympathy with the different branches of science, and well informed as to their progress. She had for several years resided in Florence, where she died at an advanced age.

Arnold Escher de la Linth was a son of the celebrated Courad Escher, surnamed de la Linth on account of the great service he rendered to the valley of that name, by directing the river Linth into Lake Wallenstadt, in order to protect the valley from inundations; an admirable work, managed with great talent and perseverance.

Arnold Escher acquired at an early age, under his father's tuition, a love for the natural sciences. Conrad Escher was in fact one of the most eminent naturalists of his time; his observations in regard to the dispersion of erratic bowlders, and their distribution over the Swiss plains, are especially remarkable.

The son, during the frequent excursions made with his father into the mountains of Glaris, formed the conception of a geological map of Switzerland, which he afterward executed and published, in concert with M. Studer, the eminent geologist of Berne, after twenty years of labor and innumerable journeys. He examined the Alps in every detail, and the precision and justice of his judgment, the accuracy of his observations, and the quickness of his comprehension permitted him to accumulate more abundant material for study than unfortunately he could make use cf.

The desirable qualities we have mentioned inspired confidence, and he was frequently consulted; his answers were always characterized by

a straightforward integrity, and a scientific accuracy quite exceptional, as well as a liberality rarely met with, which rendered him indifferent as to whether or not his ideas were appropriated by others. The perfect honesty and great conscientiousness with which he pursued his researches often prevented him from publishing them. He was always afraid of not having sufficiently investigated the ground gone over, and would go again to places he perhaps had previously visited many times.

He belonged to the geological commission of Switzerland, and was one of its most influential members. This commission assigned to him the preparation of the part of the Federal Atlas which contained the Sentis. He had devoted more than twenty years to the study of this mountain, and as early as in 1848 the cuts furnished to Murchison, which were pub lished in the memoir of the English savan, prove that he was master of the subject. When death prevented Escher from making the publication which had been intrusted to him by the commission, the latter found among his papers, with many inestimable scientific treasures, enough documents to prepare a large special map of Sentis, on a scale of fifty thousands, (the ordinary maps of the commission were of one hundred thousands,) with text, both almost entirely from the hand of Escher, a work which reflects much honor on his memory.

I should also add that Escher joined MM. Martins and Desor in an expedition to the desert of Sahara, the results of which, especially those which relate to the meteorological influence of the simoon, or wind of the desert, upon the meteorological condition of the Alpine regions, were given in the account of the expedition published by M. Desor, under the form of letters addressed to M. Liebig and M. Ch. Vogt.

A description of Arnold Escher would be very incomplete were it confined to an account of his scientific life. The integrity and love of truth which distinguished him in his researches, he carried into his private relations, where they were associated with great simplicity of manner, and, we may say, perfect amiability, accompanied by a slight diffidence, which only rendered him the more attractive. It was a real pleasure to see him enter our reunions of the Helvetic Society of Natural History, into which he brought a warm and cheerful kindliness it is impossible to forget. The void made by his death has been deeply felt, and in the month of August last, at the Fribourg meeting, every one deplored his absence, with that of our excellent colleague Pictet de la Rive. It was a great sorrow not to meet again the two friends, lately so full of life, and with nothing about them to indicate premature death.

If the society lost none of its ordinary members during the year that is passed, it added several to its number. MM. Emile Ador, Edmond Sarasin, and William Barbey were elected as ordinary members, on account of interesting communications made by these young savans in regard to organic chemistry, geology, and botany. M. Casin, professor of the lyceum of Charlemagne, well known for important researches in physics, of which he in person made an exposition, in part, at

a session of the society, was elected an honorary member. The society has chosen as president, for the year commencing to-day, Professor de Candolle, and has re-elected as treasurer, for three years dating from the month of January, M. Philippe Plantamour. Finally, it has acquired two new free associate members, MM. Edouard Des Gouttes and Henri Hentsch.

The second part of volume xxi of our memoirs appeared at the end of 1872; it contained, besides the report of the president, an article upon the Lepidoptera of the Museum of Geneva, by M. Guénée, whom the society elected last year as honorary member; the fourth series of a work by M. Duby on new, or not well known, cryptogams; some observations upon a primordial group of plants (appendiculaires) of the Strait of Messina, by M. Hermann Fol; and, lastly, an important memoir upon the effects of lightning upon trees and ligneous plants, and the employment of them as conductors or lightning-rods, by M. Daniel Colladon.

Independently of the first part of volume xxiii, which will appear in the course of the year, the society, thanks to the generosity of M. Claparède, sen., and of his daughter, Madame Flournois, has added to its memoirs, as volume xxii, the last work of M. Edouard Claparède, prefaced by a biographical notice of our lamented colleague, by M. Henri de Saussure. This volume, which is already printed, will soon be given to the public.

The society is still occupied with investigations in regard to the lake of Geneva, and has received several reports of the commission from M. Alphonse Favre. After allotting a sum of 500 francs from its funds to commence this work, in order to defray the subsequent expense the society has opened a special subscription, which has brought in 1,800 francs net. The first soundings undertaken by M. Favre, assisted by M. Henri Hentsch, cost 336 francs 75 centimes, which sum was taken from a donation to the commission of 700 francs-400 from the Geneva society and 300 from the Vaudois society. In the following account of the labors of the society will be found some of the scientific results obtained.

I mention, merely to recall the fact, the examination made by the society of the changes proposed by the central committee of the Helvetic Society of Natural Science in the existing constitution and title of the society. It has given an opinion unfavorable to their adoption, especially that which relates to a diminution in the number of days of a session, which the committee proposed to reduce to two. The society has always admitted that the local committee could, when desirable, make this reduc tion.

SUMMARY OF SCIENTIFIC LABORS.

1. Physical science.-The mathematical sciences which, without a strict regard to the laws of classification, I enter under the head of physical science, have been well represented in our sessions.

M. Galopin has given us a method of determining the maxima and the minima of a function. It consists in reducing to 0 the derivative of the function, and then arranging the roots in the order of their powers. In this order they correspond alternately to a maximum and a minimum, so that it is only necessary to determine the derivative of one of them.

M. de la Harpe has exhibited a property of numbers by which it results that the cube of one number is always equal to the difference of the squares of two other numbers.

We commence the enumeration of the works of the society in physical science proper, with meteorology.

M. Plantamour has given a summary of the udometric observations for the meteorological year 1872. From the commencement of our regular observations, that is to say, from the year 1826, there has never been as much rain in one year as in that of 1872. The ann ual mean at Geneva is 824mm. In 1872 there fell 1,086mm; that is to say, over a third more than the mean.

M. Plantamour has kept the society informed in regard to the geodetic operations carried on in Switzerland. The purpose of the geodetic campaign of 1872 has been to determine the co-ordinates of the Gebris, in the canton of Appenzell, the Gebris being one of the points of the new international triangulation, intended to connect this mountain with the Austrian triangulation. An error in the closing of a large polygon passing through the Simplon and the Gothard necessitated a new set of operations, for there was an error in taking the level of about 1", which was inadmissible. The cause of this error has not yet been discovered. The errors which are found out by the closing of a polygon have also been the subject of a communication from General Dufour, who has mentioned the deviation of the plumb-line, on account of the neighborhood of the mountains, as a possible cause of the want of accordance between the two levelings.

Our society, in concert with the Vaudois Society of Natural Sciences, has decided, as you know, to undertake an examination of the bottom of the lake. In view of this work, MM. A. Favre and H. Hentsch have made some preparatory soundings, which have been the subject of a communication to the society. The process of determining a profile by soundings, which consists in causing an experienced rower to give the same number of strokes of the oar between two consecutive soundings, is not sufficiently precise; at least it did not prove to be so under the conditions in which the observations were made. Under other circumstances it might be useful. If, on the contrary, the profile is obtained by means of a rope supported by corks, results may be corrected by a second operation. The depth of the little lake is in some parts much greater than is indicated in the map of the canton.

I am constrained to mention in this connection the communication by M. Chaix of a hydrographic map, published by the federal bureau, to

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