458 S. P. Langley—Transit of Mercury of May 6th, 1878. 
spot nuclei, being gray, slightly inclining toward a blue, like 
; t may be that this 
measurements with a Jamin photometer were unsatisfactory. 
Subsequently, by another method, a trustworthy value was 
fixed fora minimum. It was thus found that the light actually 
received on the paper apparently from the so-called “ black” 
body of the planet, at any rate exceeded eight per cent of that 
from direct sunlight, and measures taken by the thermopile and 
pcpbbveeasn showed that heat was coming from the same 
irection. 
* Monthly Notices R. A. S., vol. xxix, p. 26, 
+ I presume that even in absolutely perfect definition there would be theo- 
- al, ae prety Seen 
