178 8S. P. Langley—Selective Absorption of Solar Energy. 
We have been measuring thus far ‘“‘ heat” by which we mean 
the solar ee as interpreted by certain agents (that is, a 
lampblack, ete.), in our apparatus. In the degree in whie 
have above sintinated the selective absorption peculiar to it 
of these agents, are we entitled to speak of the resultant values, 
ee oe to the abeplate energy cu 
rections being se the: Boat values of noon 
cP eS 33 Allegheny becom 
TABLE VI.* 
A= 3175-400 450 500 600 -700 -800 900 1°00 
= Bp an 1881, 192°6 363-4 579°3 767-9 724-9 527-9 3383 215-4 173% 
d,, ring, 1881, 111-9 235-4 423°7 569°6 621°0 552°5 372°3 238°0 2346 
The mean air mass for winter = 13°88 
spring = 9°33 
We now proceed to the calculation of the energy outside the 
atmosphere for homogeneous rays with the data which have 
been given. For this purpose we have used the formula 
ee ee d,—M, f, log. t. 
deflection at n or the same ray, a the natoomntet pressure 
in units of one BS dacimetey or the mass of air in the vertical 
column ; the co rresponding air-mass for the sun ’s sp 
ssion, to show the relation between energy outside the 
See and Bae high and low sun at “Allegheny, the 
BE VII. 
*BI5 ry “450 -500 “600 -700 °800 °900 1-000 
A= 
K =energy before a 353 683 1031 1203 1083 849 519 316 309 
d, =energy after absorptio 
(corrected high sun), 112 235 424 570 621 553 372 238 235 
bsorption 
corrected low sun), 27 63 140 225 311 324 246 167 167 
* Tt will be seen that riety the winter absorbing air-mass was nearly half 
ge again as in the s ben eat mesh from the shorter wave- -lengths 
was actually greater in 
sf 
REO RS IE i 
