[ G5 ] 

 XY. Proceedings of Learned Societies, 



EOYAL SOCIETY. 



Jnn. 12. J. HE President in the clniir. — The conclusion was read 

 of Mr.Travers's elahorate and in2;cnioiis paper on the mechanism 

 of tlie eve, and the means bv v>hich this organ obtains distinct 

 vision of obiects at different distances. In conchiding, he took 

 a summary view of the principal hvpothescs formed to explain 

 this phaenomenon, such as the muscles of the eye, the ciliary 

 processes, and the supposed muscles of the lens itself, by which 

 it was capableof receiving distinct images of objects at diiierent 

 distances. All these opinions Mr. T. showed were totally in- 

 compitible with the facts demonstrated by anatomy ; he also 

 proved that the supposed influence of the will over the muscles 

 of the eye, impelling them to contract or dilate at pleasure, 

 can have no better foundation, as tlie mechanical action of 

 light on the eve jjroduced this effect without any regard and 

 often even in direct opposition to the v.ill, and is attended with 

 a painful sensation in the eye : besides, this sup])ositiori assigns 

 two causss for one effect, which is iniphilosophicai as well as 

 contrary to phvsical experience. Mv. T. then described the 

 anatomical structure of the eve, observed the muscular appear- 

 ance of the iris (Bcrzelius in his Animal Chemistry considered 

 this organ as nmscular), inferred that there is a sphincter mus- 

 cle, and that this muscle produces an external pressure on the 

 lens, which alters its shape, and thus effects distinct vision by 

 adjusting the pupil to different foci. The contraction or dilata- 

 tion he considered as being always in proportion to the quantity 

 of light reflected from external objects, and not according to 

 the ^viil of the observer. The crvstalline lens, being more fluid 

 in youtii than in old age, sufficientlv accoxmis for the diversity 

 of vision in those stages of human life. As the nearer objects 

 are to the eye, the more thev reflect light on it, and hence the 

 painful sensation is occasioned by continued looking in this si- 

 tuation. 



Jan. 19. A letter from Dr. Brewster to the President was read, 

 containing an account of some more experiments, by this inde- 

 fatigable philosopher, on the effects of compressing animal sub- 

 stances which depolarize light. The principal expfriment was 

 on calf's foot jelly cut into a columnar form and compressed 

 between two plates of glass ; at first no depolarization of light; 

 took place ; but alter the jelly had remained ten days between 

 the glasses, and accpiired a consistency almost approaching that 

 cf caoutchouc, the edges evinced the commencement of depola- 

 rization; and when the whole mass had attained a uniform dcn- 

 Vol. 45. No. 201. Ja;/. 1815. E sity, 



