Chemistry and Physics. 401 
conditions necessary for producing the appearance of curvature. 
number of well-known men of science. 
in regard to the combination of points differing in retinal 
latitude, the only appeal is to experiment. My observations 
corroborate those of Professor Rogers and of Helmholtz. e 
nature of the experiment seems to have been misapprehended 
by Mr. Backhouse. It invalidates the theory of corresponding 
os if any mathematical significance is to be attached to this 
theory. 
mat 
Brooklyn, Oct. 3, 1883, 
Neier 
SCIENTIFIC INTELLIGENCE. 
, J. CHEMIsTRY AND Puysics. 
n Homologous Spectra.— 
re, to mean possessing 
lo 
oO 
7 
3 
oO 
=| 
R 
[as] 
hm * 
ot 
— 
5 
=) 
7) 
an affinit ion. 
resemblances in spectra had been observed by Mitscherlich, by 
Lecog de Boisbaudran and especially by Cimician. The latter 
