( 609 } 
and on the morning of the 18 very discordant deviations of the 
galvanometer were obtained, clouds continually passing before the sun. 
During the time between the first and second contacts only 26 
determinations of radiation were made at moments when the clouds 
were not too thick. The direct radiation of the sun on the little 
thermopile at 105 46m 105, (i.e. “about 20° before first contact) 
amounted to 1762000. The diminution which in the case of clear 
weather could have been followed step by step, now of course took 
place very irregularly. At 12) 18™ 548, i.e. 618 before second contact 
we observed through the clouds an intensity of radiation of 604. 
After the beginning of totality the thermopile was directed in 
succession to four points of the sky, situated to the North, East, 
South and West of the sun, each at a distance of 3° from the disc, 
and between each of these exposures it was exposed to the corona. All 
these fields were filled by clouds. The readings of the galvanometer for 
the four fields round the corona showed irregular differences (varying 
between — 9 and + 1 scale-divisions) compared with the readings 
for the central field. It was not possible to derive from the oberva- 
tions an estimation of the radiation of the corona, but the numbers 
obtained seem to point to the conclusion that the radiation of the 
corona cannot be much larger than the observed differences between 
the radiation of neighbouring groups of clouds. The full moon would, 
in a clear sky, have given a deviation of 22 or 23 scale-divisions ; 
the radiation from the corona seems to be of the same order of 
magnitude. : 
One thing is certain, viz. that our results cannot be made to 
agree with the opinion of DESLANDRES that it is possible to measure the 
heat-radiation of the corona without an eclipse (C. R. CXXXI p. 660). 
After third contact the surroundings of the sun were comparatively 
clear for a few minutes, but soon afterwards the clouds came on 
again. The observations were continued at intervals to 12 12m when 
they were discontinued, the results being considered untrustworthy. 
The large influence of the clouds on the heat-radiation is shown 
by the fact that 8 minutes before 224 contact the transmitted 
radiation was 455, while 8 minutes after 3"¢ contact it amounted 
to 74300. , 
Every precaution had of course been taken to make the instru- 
ment practically insensible for alterations of temperature in the 
neighbourhood. Alterations within the above mentioned field of 
3° diameter were the only ones that were recorded by the galvano- 
meter. 
