Scientific Intelligence — Geology, 391 



he has seen no trace of Silurian formation in the sides of the canal. 

 He only found, to the east of Kilia, a very curious formation of 

 sedimentary rocks, the beds of which, highly elevated, appeared to 

 be composed of the same elements as the igneous rocks in contact 

 with them, and which seem to belong to the trachytic family. 



M. Ilommaire has determined the saltness of the Black Sea, at 

 different points, by means of M. Callardeau's densimeter, and by 

 the more exact method of evaporation, and weighing the containing 

 vessel when empty, full, and with the residuum. The results have 

 been sensibly the same everywhere, and presented scarcely any dif- 

 ference from those of the Bosphorus. 



M. Hommaire has sought to verify the existence of a great cur- 

 rent which is generally admitted to flow towards the Bosphorus, and 

 which is attributed to the superabundance of the waters which the 

 Danube and the great rivers of Southern Russia discharge into the 

 Euxine sea. He has found no trace of this current, and yet he has 

 sailed along the shores of the Black Sea for upwards of 300 leagues. 



M. Hommaire de Hell is likewise occupied with the level of the 

 Bosphorus. An investigation made with the utmost care, by means 

 of a proper instrument, has proved that there is no sensible dif- 

 ference of level between the Black Sea and the Sea of Mai-mora. 

 rrdmE.oumelikavaktoBacta-Liman,adistance of upwards of ISOOO'", 

 the declivity being towards the south, and while the winds were from 

 the north, it did not exceed 0™'0326. 



The observations he has made on the direction and quickness of 

 the currents, at different depths, have indicated a general direc- 

 tion towards the south. He has been struck with the rapidity with 

 which the current sets in towards the south, even to a depth of 25"", 

 as soon as the north winds begin to blow. It might then be said 

 that the waters are displaced in a single mass, throughout their 

 whole height, to be conveyed towards the Sea of Marmora. He has 

 likewise noticed a faint southern current at the surface, diminishing 

 by degrees till it is reduced to zero, to a depth of about 15°S to re- 

 appear in the same direction at 18 or 20™, with a celer'ty tenfold 

 that of the surface. In order to explain this phenomenon, M. Hom- 

 maire supposes that there first existed, under the influence of strong 

 winds from the north, a current towards the south, embracing nearly 

 the whole height of the canal. South winds having succeeded these 

 north winds, the current would become completely neutralised in the 

 superior beds ; but before the reaction could descend into the lower 

 regions, the south wind would have resumed ; hence the new cur- 

 rent towards the south, at the surface, and even to a certain depth. 



After all these investigations, it seemed of consequence to the 

 author, towards the interest of his researches on the geological revolu- 

 tions of the basin of the Euxine, to determine whether, in the case of 

 the clusiiig up of the Bosphorus, the waters of tlie Black Sea, on 

 rising, might find an outlet in the Sea of Marmora, by ascend- 



