W. LeConte Stevens—The Stereoscope, ete. 443 
table I—indeed comparison of a larger number ie observations 
yielded a larger coefficient. Accordingly, since the tempera- 
errors arising from this cause. Thus, the actual diminution of 
terrestrial temperature from equator to pole is about £0° accord- 
ing to Dove, while it would eo pa a 212° if Brspericns! to 
the solar accession as computed by Meec ucing the 
figures 4°83° and 21°55°, ies “from tables TI and III 
veered in the ratio of 212: 80, yields 1°82° and 8°18° as 
tolerably trustworthy values for the diminution of mean tem- 
perature effected by the operation of the law stated at the 
outset. 
and those derived from observation pone eo the conviction’ 
that the paane detailed in the foregoing pages must be 
valid. Appiy then the second value to the earth when the 
eccentricity is near its superior limit, it appears that the hemis- 
pheres should vary in mean temperature by no less than 16°— 
that secular summer should prevail in one, while the other was 
enshrouded in the snows of its secular winter. The importance 
of the agencies eh eo will perhaps be more manifest when 
it is borne in mind that during its secular summer more solar 
heat and light is received by a hemisphere in winter than in 
summer, while on the opposite hemisphere the solar accession 
is no less than 114 times greater in summer than in winter. 
Art. LVIIL—The Stereoscope, and Vision by Optic’ Divergence ; 
by W. LECoNTE STEVENS. 
{Continued from page 362.] 
e 
termine the judgment of distance, and the significance of this 
* This Journal, Nov., 1881. 
