FOR THE ADVANCEMENT OP SCIENCE. 121 



after death, the lenses being placed in distilled water, as being the 

 only fluid which did not affect the transparency of the cepsili. 

 From these investigations Sir D. Brewster has been led to conclude 

 that there is in the crystalline lens a capability of being developed 

 by the absorption of the aqueous humour, that a perfect structure is 

 not produced until the animal frame is completely formed, and that 

 when it begins to decay the lens changes its density and focal 

 length, and sometimes degenerates into that state called hard and 

 soft cataract. Sir D. Brewster is led to entertain a hope that these 

 researches may furnish a means of preventing or curing this alarm- 

 ing disease. 



The Rev. Mr. M'Gauley having been called on by the president to 

 read a paper in continuation of the one which he gave last year, 

 respecting the theory of the Application of Electro-Magnetism to 

 Mechanical Purposes, commenced by stating that he had met with 

 many practical difficulties, as might be expected, in preparing for 

 the section a small model of a machine, intended to act with effec- 

 tive power ; one of the most serious of these was, that the crank and 

 fly-wheel could not be made to move along with the primary mov- 

 ing pendulum. He then proceeded to give his views of the theory 

 of electro-magnetic influence, and the best modes of constructing 

 the several parts of the apparatus, so as to produce the greatest ef- 

 fect, and illustrated the subject by copious extracts from a most labo- 

 rious course of experiments, which it would appear that the reve- 

 rend gentleman had himself instituted and conducted. 



At the termination of the reading of this paper, which extended 

 to great length, Professor Ritchie made some observations on its 

 want of novelty ; and stated that every part of the theory, and all 

 the experiments had appeared in several of the most widely cir- 

 culated scientific journals.* 



Wednesday. — The business was commenced by Mr. Harris, 

 w On some Phenomena of Electrical Repulsion." 



Professor Challis's Supplementary Report on the Mathematical 

 Theory of Fluids gave an account of the application of mathema- 

 tics to problems in the equilibrium and motion of fluids, which had 

 not been touched upon in the author's previous reports. These 

 were principally the mathematical theory of elastic fluids, as bearing 

 on the determination of the heights of mountains by the barome- 

 ter, the amount of astronomical refraction, and the theory of the 

 the determination of the velocity of sound as affected by the de- 

 velopment of heat. The bases on which these theories rest were 

 stated, and a comparison made of the theoretical results with expe- 

 riments. 



Mr. Adams made a communication on the Interference of Sound. 

 He made some pleasing experiments with a tuning fork and a small 

 glass tube, one end of which was closed. When the fork was held 



* Mr. M'Gauley has published a letter in The Athenceum, complaining of 

 this bitter and unfounded attack on his theory after he had quitted the room. 

 VOL. V. NO. XVII. Q 



