402 



SCIENCE. 



[Vol. II., No. 33. 



Mr. Casimir de Candolle repeated, before the mem- 

 bers who were present, some experiments to show 

 how sand-ripples at the bottom of our lakes are 

 formed. These facts were applied, in accordance 

 with the ideas of Professor Strasburger of Bonn, to 

 explain certain appearances of envelopes and vege- 

 table cells in fossils. 



Mr. Raoul Pictet presented an experimental demon- 

 stration of the second law of thermo-dynamics, 

 deduced from the simultaneous working of steam- 

 engines and frigorific apparatus. 



Professor Weber of Zurich presented two interest- 

 ing papers: one, on a dynamic method for the exact 

 measurement of the coefficient of conductibility of 

 heat in liquids ; the other paper, on the apparatus for 

 measuring electric units. 



Mr. H. Dufour of Lausanne distributed among 

 the audience a set of photographs showing the electric 

 condition of the air, which were obtained by means 

 of a registering electrometer in the new physical 

 laboratory at Lausanne. These curves are so con- 

 nected with the condition of the heavens, that it is 

 no exaggeration to expect to predict the weather 

 several days in advance, through a careful examina- 

 tion of the variations of electric tension of the air. 

 For fine weather, the electric tension is strong; it 

 sensibly decreases during and before storms; the 

 rapid falling of the curve of the electric potential of 

 the air is always an indication of rain or storm. 



The late hour made it impossible to listen to five 

 additional communications which had been an- 

 nounced. The boat for an excursion on the lake 

 awaited its guests; science paled before the beauties 

 of nature. Though continuing to converse on the 

 subjects treated, we all together betook ourselves to 

 the pier. The excursion was delightful. On our 

 return, the streets were illuminated; Bengal and elec- 

 tric liglits mingled tlieir dazzling rays. The citizens 

 of Zurich gave us a magnificent reception; and the 

 Jete, enlivened by an excellent orchestra, was con- 

 tinued to a late hour. 



The next morning, Thursday, we listened to three 

 scientific papers which closed the intellectual part 

 of the reunion. 



The honors of that morning belong to Professor 

 Suess of Vienna. With consummate skill he set 

 before us the chief points of the modern theory of 

 the upheaval of mountains: he held his audience 

 with great ease, and left a refreshing memory with 

 all who heard him. 



This paper, with that of Mr. Heer which followed, 

 will be issued in full in the memoirs of the society. 



The afternoon was given up to leave-takings. 

 Seated around the long tables of the hotel L'Uetliberg, 

 thanks and farewell were said again and again. 

 Toasts of gratitude, toasts to the absent, to the pres- 

 ent, to Clausius, to Mousson, Oswald Heer, and 

 Studer, founders of the society, were applauded by 

 all, glass in hand. 



Appended to this account, appears a list of the 

 principal papers offered in the other sections. 



In the botanical section. Professor Heer spoke of 

 the cretaceous and tertiary flora of Greenland; Mr. 



Schnetzler, of a Chinese primrose in which the sexual 

 organs corresponded to an earlier stage in the evo- 

 lution of Primulaceae, and on certain relations be- 

 tween an aerial alga and lichen; Mr. Favrat discussed 

 the hybrids of two species of primrose and of other 

 plants, and called attention to the changes in a Car- 

 damines growing in turfy soil. Mr. Andreae spoke 

 of pasturage on the Jura; and Mr. Casimir de Can- 

 dolle drew attention to a curious Cytisus bearing both 

 red and yellow flowers. 



In the chemical section. Professor Krafft read a 

 paper on the preparation of saturated alcohols; 

 Professor Soret, on the absorption of the ultra- 

 viole rays by the albuminoid substances; Professor 

 Scliulze, on tlae composition of clieese; and on 

 phenylamido-propionic acid; Prof. Victor Meyer 

 gave a new method for determining the vapor density 

 of CI. Br. I. for high temperatures, and reported on 

 a new series of bodies, which he termed tlnjoplieneK, 

 contained in benzol. Professor Wislicenus of Wurz- 

 burg offered a contribution to the theory of Van 

 t'Hoff; and made a communication on the action of 

 chloride of phtalyle and of phtalic anhydride on the 

 ethers of malic acid; Professor Schaer recalled the 

 forgotten works of De Salve (in 1756) on zinc com- 

 bustion; Dr. Goldschmidt showed the action of 

 hydroxylamine on ketones ; Dr. Ceresole spoke of 

 acetacetic acid; Professor Lunge, of the manufacture 

 of sulphuric acid; Dr. Schumacher gave analyses 

 of foods; and Dr. Urech exhibited a laboratory- 

 lamp. 



In the geological sections, papers were offered by 

 Messrs. Favre, Neumayr, Schardt, Goll, Miihlberg, 

 Fellenberg, Jaccard, Koch, Chevannes, Mosch, 

 Fratech, and Suess. 



LETTERS TO THE EDITOR. 



*4:* Correfipondentaareregueatedto beaabrif/aii ponaililf. The 

 writer^s name is in all canes required as proof of good faith. 



Geology of Philadelphia. 



In Dr. Frazer's notice of my lecture upon the 

 geology of Philadelphia, there is so little of adverse 

 criticism, that it may seem ungracious to reply to 

 tlie few points regarded as blemishes. Merely in 

 defence of the use made of certain terms called in 

 question, a few words liere may not be out of place. 



In describing the Philadelphia gneiss as both Ha- 

 ronian and Mont Albaii, there is no confusion, if, as 

 is held by many geologists, the former term is genei'ic, 

 the latter specific. 



The term ' creep,' as applied to the puUing-over 

 of softened or broken strata downhill, by the action 

 of gravity, frost, etc., is one frequently used in de- 

 scribing such phenomena in regions south of glacial 

 action. It is used repeatedly in this sense, in a report 

 issued by the Geological survey of Pennsylvania, in 

 1880. 



The term ' hydro-mica slates,' objected to, is not 

 only used by Rogers, Lesley. Dana, Hall, and others, 

 but occurs repeatedly in Dr. Frazer's recent geolngical 

 reports on Lancaster and Chester counties, being 

 used by himself. 



The positive statement regarding the absence of 

 glaeiation in Pennsylvania south of the terminal mo- 



