596 
THE EAEL OP EOSSE OH THE EADIATION 
As the moon was not observed at a less zenith-distance than 29°, Seidel’s value of <pz 
for 29° was adopted: it is almost needless to remark that all the observations might 
equally well have been reduced to 29° zenith-distance as a superior limit; the only effect 
would have been to lessen all the subsequent numbers of this paper by part. With 
the help of the above Table all the observations were reduced to the zenith, and a mean 
zenith value for each night obtained. From these mean zenith quantities the mean 
values corresponding to the altitudes at which observations had been taken were calcu- 
lated, and logarithmic differences formed exactly as had been done with the observa- 
tions. These differences were now compared with those derived from observation, and 
from them was drawn the following list of the outstanding errors (C — O), expressed in 
units of the fourth place of decimals, where the sign -f- represents a greater absorption 
of radiant heat in the lower regions of the atmosphere at the time of observation than 
under average circumstances. 
Comparison of observations with reducing curve in zenith-distance. 
1871. 
Zenith-distances. 
c-o. 
1871. 
Zenith-distances. 
C-O. 
O O 
O O 
Mar. 2. 
61*4 68-7 
- 304 
Apr. 30. 
45-1 47-8 
- 210 
„ 73-0 
- 80 
„ 54-2 
- 79 
„ 76-6 
- 218 
„ 67-1 
- 97 
„ 73-4 
- 356 
Mar. 27. 
42-5 43*3 
- 355 
„ 78-8 
-1137 
„ 47-8 
+ 56 
„ 51-7 
+ 213 
May 3. 
62-3 66-3 
+ 18 
„ 55-1 
+ 260 
£9.9 
+ 673 
May 28. 
59*8 65-2 
+ 1 
„ 65 - 3 
+ 887 
„ 70-1 
- 178 1 
„ 71-4 
+ 552 
„ 74-9 
+ 240 
„ 74-4 
+ 359 
„ 77-7 
+ 291 
„ 77-5 
+ 530 
„ 79-6 
+ 173 
Mar. 28. 
43-3 46-1 
- 34 
May 29. 
57-0 60-2 
— 122 
„ 59-9 
- 573 
„ 64-1 
+ 167 
,, 62*5 
- 474 
„ 78-5 
+ 604 
„ 64-9 
- 83 
„ 67-6 
- 373 
May 30. 
68-3 76-6 
- 99 
„ 73-0 
- 682 
„ 75-2 
-1228 
June 1. 
69-7 71-0 
- 64 
,, / 3 - 3 
— 85 
Mar. 29. 
39-0 41-4 
- 12 
„ 79-4 
- 105 
„ 43-5 
+ 65 
„ 58-9 
+ 259 
June 2. 
73-8 74*2 
- 725 
„ 61-8 
+ 195 
„ 74-3 
- 683 
,, 65*2 
— 143 
„ 67-3 
- 352 
Nov. 1. 
41-5 49-9 
+ 275 
„ 70-7 
+ 116 
„ 52-8 
+ 425 
„ 74-3 
+ 334 
„ 55*3 
+ 76 
„ 76-8 
+ 543 
Dec. 19- 
57-8 59-6 
- 97 
Apr. 3. 
46-0 46-4 
- 121 
„ 60-7 
- 50 
„ 46-6 
+ 24 
„ 48-2 
- 31 
Dec. 20. 
49*5 49-7 
- 288 
„ 53-9 
+ 22 
„ 49-9 
+ 41 
„ 621 
- 539 
„ 50-0 
- 7 
„ 67*5 
- 31 
„ 68’5 
- 301 
„ 75‘8 
+ 286 
,, / 5 • 8 
- 612 
| 
M / J 
- 634 
