472 British Association for the Advancement of Science, 



debted to M. Adolphe Brogniart, — than the appHcation of Mr. 

 Witham's ingenious method of detecting the structure of fossil 

 vegetables ; we think it will, ere long, be generally applied to 

 all doubtful fossil substances. 



Mr. Phillips concluded the morning with a paper from Dr. 

 Henry, on the roasting of the copper ore of Anglesea. Th6 ore, 

 when roasted, gives lumps, which contain from thirty to fifty 

 per cent, of copper ; these are picked out and then smelted. 

 The Archbishop of York was present during a part of these pro- 

 ceedings. In the evening the Rev. Mr. Scoresby delivered to a 

 very numerous assemblage of ladies and gentlemen, the result of 

 his experiments on the law of magnetic induction : the magnetic 

 force diminishes with the square of the distance ; and he has in- 

 vented a method of applying the magnetic influence to the ad- 

 measurement of rocks and solid substances in situations where 

 these are not, by known methods, measureable. The applica- 

 tion of this curious branch will probably become of great value 

 in mining operations. Many rocks occasion a sensible deviation 

 of the needle, and it is probable that when we are better ac- 

 quainted with the magnetic intensity of the various rocks, we 

 shall be able to measure their thickness. Mr. Scoresby has 

 found that he can, by his own magnets, cause an angular devia- 

 tion of the needle, from a distance of sixty feet, through the 

 most solid substances. 



On the morning of Friday the 30th, Dr. Brewster communi- 

 cated an interesting paper on the structure of the crystalline lens in 

 the eyes of fishes. The various arrangements of this structure, 

 adapted to the wants of these animals, through their extensive 

 distribution in the waters of the globe, are extremely instructive 

 and curious. To this communication succeeded a very lively 

 geological discussion, in relation to certain marine shells, of ex- 

 isting shells of mollusca, found in gravel pits about Preston in 

 Lancashire, and which, it appears, are elevated three hundred 

 feet above the level of the sea. There is a communication on 

 this subject at p. 170, Vol. III. of the Magazine of Natural His- 

 tory, from the Rev. Mr. Gilbertson, who had collected these 

 shells as early as 1829. Mr. R. C. Taylor also has two notes 

 following the same communication. The country appears to be 

 covered with, a marl, and, according to the observation of Mr. 

 Murchison, the sands, marls, and gravels, have no deposit super- 



