Art. I. — A Neiv Form of Circuit Closer for the Firing 

 of Torpedoes. 



By R. E. Joseph, Esq. 



[Read 11th April, 1878.] 



Art. II. — Photographs on the Retina. 

 By James Jamieson, M.D. 



[Read 11th April, 1878.] 



At the meeting of the Berlin Academy of Sciences, on 23rd 

 November, 1876, there was read a communication from Pro- 

 fessor Franz BoU, of Rome, on the subject of some remark- 

 able properties of the retina, which had not till then been 

 described. He experimented first with frogs, in the follow- 

 ing manner : — A frog, which had been kept for some time in 

 the dark, was beheaded, and its eye removed as quickly as 

 possible. The front of the eye was cut off with scissors, 

 and the retina lifted from the dark layer behind, when it 

 was seen to be of an intense red colour, which rapidly faded, 

 so that in ten to twenty seconds it had disappeared. For 

 the next thirty to sixty seconds the retina had a sa.tiny 

 lustre, which also gradually disappeared, leaving the struc- 

 ture quite colourless and transparent. Boll found that the 

 colour has its seat in the rods, and not in the cones ; and 

 that it is found in all animals in which there is a well- 

 developed layer of rods. Even in the rods it is confined to 

 the outer portion, which is made up of thin plates. Along 

 with these red rods BoU found a smaller number of green 

 ones, which also undergo some changes of shade under the 

 influence of light, but which have not had their properties 

 well investigated; and he had not, indeed, been able to 

 discover whether they occur in any other animals than the 

 amphibia. He tried the effect of exposing the eye to light 



