Technical Physics. 285 
surface of one side of a lamp-shade, of any form, would be compensated for by that 
sila hs pag from the opposite side—and that no similar compensation could 
occur in my own experiments where only ingle sheets of glass were used,—is evi- 
dea ‘but Tam ignorant of any experiments 1 which go to show that the amount of 
which is cut off fr 
ent “ah that which ead be stopped by § a s curved screen of the same itty tig Let 
a : out 
ire and, having interposed the apparatus s between a flame and the photometer, 
oe - re uch light is cut off by th e glass, i. e., bring the photometer to rest, 
w, h s and fasten 
Tess j in case than in the a supposition accordance non received 
eories (see Art, Light in “Boeyelopedin Meola, p. 847, $$ 42, 48); nor 
would it be cr om what 3 is known of nalogous cas e of radiant nie 
i screens, 
As for the experiment of Prof. Verver, to which Mr. King takes pai he 
must e pply to the 
‘ er is in some 
the orien: he be entirely exempt from the same se eng me 
as of Verver. In making this fotvark, I would not in the least 
tered that 3 Mr Ben § yotheine are not most excellent. For my own part, I en- 
to no doubt of thei —for, thro ied ¢ ut the conceivable slight error 
whi which I hats alluded: ‘his his welhod of experimenting is pecieir bly the best 
's yet known. I urge only that the observation of a a ang not be re- 
poston, Feb. 6, 1861. 
ovr. Scr.—Srconp hn Vou. XXXI, No. 92.—Marcu, 1861. 
37 
x 
