224 Proceedings of Learned Societies. 



■weights and measures, and the centigrade division of the thermo- 

 meter, and recommended the Association to exclude all other 

 standards from their future publications ; and concluded by a 

 consideration of, and a qualified assent to, the Darwinian theory 

 regarding the origin of species. 



Many of the topics of the papers read in the different sections 

 of the Association have been already mooted in the different scien- 

 tific societies, and Lave been duly chronicled in our pages. Among 

 the most interesting of those not noticed may be mentioned that of 

 Mr. A. Claudet on the refractive power of the eye, by which objects 

 that are situated in reality somewhat behind us appear as if situated 

 to the left or right ; or, in other words, that objects are pictured in 

 the retina which are included in an angle much larger than half 

 the sphere of which the observer is the centre. 



From the refractive power of the cornea, rays passing through 

 it are more and more refracted in proportion to the angle at which 

 they strike its surface ; the only objects seen in their true position 

 being those whose rays enter the eye perpendicularly to its sur- 

 face ; rays entering at an angle of 90° are refracted 10', and appear 

 to come at an angle of 80\ 



Some curious illusions result from this law. I may suggest the 

 following experiment. Connect two lights placed at some yards 

 distance from each other by a strained thread, on placing the face 

 over the centre of the thread, and looking at right angles to it, both 

 lights are seen somewhat in advance of the body, as if forming an 

 angle of 160', and if the observer turns his back on the thread and 

 walks away from it, both lights remain visible, so long as the angle 

 formed by them does not exceed 200' ; hence we are really enabled 

 to see behind us whilst looking straight in front. 



Mr. Claudet called attention to another effect of this pheno- 

 menon. That on placing ourselves so that the sun is on one hand 

 and our shadow on the other, the sun and shadow do not appear 

 connected in one line, but that they are bent to an angle of 160% 

 and are both seen a little before us. The intellectual observer of 

 these phenomena need hardly be reminded that the head should not 

 be turned to either side during these experiments. 



The paradoxical and apparently impossible action of Giffard's 

 injector, employed instead of a feed pump in charging steam-engine 

 boilers, was illustrated in a remarkable manner by the Abbe Moigno, 

 with M.M. Bourdon and Salleron's " Injector of Solids." 



( i i Hard's injector consists of three tubes united at one point : one 

 of these brings the supply of water for the boiler from any con- 

 venient source ; the second is for the purpose of conveying the 

 water into the boiler, and opens below the level of the liquid in that 

 vessel ; the third brings a jet of steam from the upper part of tho 

 boiler. This jet of steam lias the power of injecting a constant 

 supply of water into the boiler, and so obviating altogether the 

 necessity for a bed pump, and, apparently impossible as it may 

 appear, not only has the strain power to inject water into its own 

 boiler, but it is capable of feeding another boiler in which the 

 steam has a much higher pressure than itself. MM. Bourdon and 



