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 reduction.

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 neigh borhood 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

which M. Chaix has added his experiments upon the proportion of solid matter contained in the water of the Arve.

On the 27th of November of last year occurred that remarkable rain of meteors, which seemed to confirm the hypothesis that shooting stars are produced by the disintegration of comets. M. Plantamour gave to the society the data for the solution of the question, to which the attention of the society was again directed by M. E. Gautier, in the course of a notice of the presumed discovery of the comet of Biela by an astronomer of Madras.

I complete the notice of astronomical researches by mentioning the remarkable instance communicated by M. Thury of astronomical visibility. He observed, by means of his small refractor, with great clearness, on the night of the 15th to 16th of June, the star Antarès and the small blue star near it.

Want of space permits me merely to recall to your memory, without analyzing it, the communication of M. Soret in regard to his comparative researches between thermal solar radiation and that of a body heated in the oxyhydric flame. These researches, which modify the assertions of P. Secchi in regard to the temperature of the sun, have been published. I would say here, that it is our custom, in our annual account of the proceedings of the society, to confine ourselves almost exclusively to communications which have not been laid before the public. I give, once for all, this explanation, to account for the more or less brief notice of some of the subjects which have been discussed at our sessions.

M. Wartmann discussed the theory of the perception of color, which admits three systems of nerves, corresponding to the three fundamental colors, and opposed to this theory certain observed facts; in particular, the fact that certain Daltonians do not perceive color, but only a contrast of light and shade of different intensities.

Information in regard to the aurora borealis has, from time to time, been sent to me by observers of this phenomenon and by savans interested in the subject. I have communicated to the society the principal inferences drawn from a work of M. Boué, upon the concordance of austral and boreal auroras which he sent me in a letter, and also those from the researches of M. Lovering, who has united in a catalogue more than 12,000 observations of auroras.

M. Marignac has given us the result of his experiments upon the identity of the heat of fusion and the heat of solution. The temperature of solution of a body whose point of fusion is very low was observed during the cooling, and particularly as it passed the point of fusion. There was no sudden change, nothing anomalous, as it passed this point; and M. Marignac therefore concluded that the heat of fusion is identical with that of solution. For this experiment a solution of spermaceti in alcohol was used; the point of fusion was at 48° C. The

substances which meet the conditions required by these researches are few in number.

M. E. Ador has presented to the society a summary of his researches in regard to the radical of phtalic acid.

I close the account of our labors in physical science by mentioning the oral summary given by M. Casin of some of his researches, already printed, which he has presented to the society.

I also recall that Professor Gautier in numerous reports, several of which have been published in the archives, has informed us of various astronomical investigations, and in particular of those of M. Huggins of stellar spectra in regard to the direction of the movement of stars in relation to the earth.

2. The natural sciences.-Geology and paleontology have so much in common, that it seems to me quite natural to mention in connection what relates to these two sciences.

I would remind you that M. A. Favre presented an article upon phos. phates, and their beds, and that M. E. Favre made the society acquainted with the recent works upon the structure of ammonites.

The boring of the Gothard cannot fail to interest geologists. Specimens of the different rocks encountered will be preserved in their order of succession. M. A. Favre, in making a communication to the society upon this subject, suggested the request for a set of these specimens for the Museum of Geneva.

M. Ed. Sarasin presented an article, prepared with the assistance of M. Fuchs, upon the sources of the petroleum of Câmpina, in Wallachia. This article assigns to petroleum an eruptive origin, and assimilates it to the hydrocarbons disengaged during volcanic phenomena. This hypothesis led the authors to expect that they would find in beds of petroleum a distribution analogous to that of metalliferous strata; their anticipations were confirmed by the discovery of an orientation, following two parallel lines, in the petroleum-emanations of the plateau of Câmpina.

M. de Saussure, on his return from a visit to Naples, gave us a description of the crater of Vesuvius, then in eruption, (see the Journal of Geneva,) and also presented the society with several other communications, upon various subjects, which have already been published.

M. Dor exhibited to us three skulls of the lacustrian period, recently discovered. Two of these skulls belong to the stone age, and are therefore very valuable, on account of the rarity of such specimens, a rarity probably due to the custom of burning bodies. They are skulls of the ancient Helvetians, a Celtic race. The large size of one of them shows that the stature of the man of the stone age was greater than has been supposed. The third is the skull of a child of the bronze age.

Under the head of "animal physiology" should be recorded the researches of M. Prevost upon the section of the cord of the tympanum. Contrary to the opinion first announced by M. Vulpian, and afterward