614 
THE EAEL OF EOSSE ON THE EAEIATION 
warmed at the tire in order to dissipate any accidental film of moisture, while in the 
subsequent years it was merely kept in a dry room and then briskly rubbed with cotton- 
wool before being placed in the telescope. The quantity of heat transmitted by the 
glass is greater in the former case than in the latter. 
The results for 1870 can now be arranged like those for 1871-72 ; but, in addition to 
the reductions to a mean distance of the sun and moon, the speculum-factors must be 
applied. We have thus the following summary, where 
log^corr. = log log E ,2 -f- log speculum-factor. 
Observations reduced to a mean distance of the Sun and Moon compared with Curve. 
1870. 
£. 
log 2 corr. 
z’ (obs.). 
No. of 
sets. 
1871-72. 
z' (curve). 
C-O. 
^(C-O). 
Oct. 4. 
O / 
— 54 5 
9-9443 
135-3 
3 
170-3 
+ 35-0 
+ 25-9 
Aug. 8. 
-30 19 
0-1217 
204-4 
O 
*J 
274-3 
+ 69-9 
+ 34-2 
„ io. 
- 5 59 
0-1364 
350-3 
% 
406-2 
+ 55-9 
+ 16-0 
Oct. 9. 
+ 6 40 
9-9715 
401*4 
4 
381-0 
— 20-4 
- 5-1 
Aug. 11. 
+ 8 39 
0-1448 
327-7 
3 
372-8 
+ 45-1 
+ 13-8 
Oct. 10. 
+ 16 8 
9-9756 
353-7 
3 
339-9 
— 13-8 
- 3-9 
Aug. 12. 
+ 20 19 
0-1527 
333-0 
4 
321-4 
-11-6 
— 3-5 
„ 13. 
+ 31 38 
0-1610 
250-3 
5 
271-1 
+ 20-8 
+ 8-3 
„ 14. 
+ 43 2 
0-1681 
283-8 
3 
220-6 
-63-2 
—22-3 
„ 15. 
+ 54 35 
0-1722 
196-6 
3 
173-2 
-23-4 
-11-9 
„ 16. 
+ 65 47 
0-1737 
163-0 
3 
138-4 
-24-6 
— 15-1 
„ 19. 
+ 99 16 
0-1674 
57-4 
3 
56-0 
— 1-4 
— 2-4 
z' (obs.) is the zenith -value of the total heat for a mean distance of the sun and moon 
and for an average speculum ; 
z' (curve) is taken from the curve derived from the results of 1871-72 ; 
C — O is the difference between curve and observation, and ^(C — 0)is the percent- 
age difference. 
The deviation of the total heat-results from the curve of 1871-72 are within such 
moderate limits, that, taking into consideration the way in which the speculum-factors 
were derived from it, it does not appear advisable to alter its course in order to attempt 
a still closer representation of the whole of the observations. 
The following Table gives a summary of all the observations made with the glass 
plate interposed, during the years 1870, 1871, and 1872, of which the preliminary reduc- 
tions have already been given. 
