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TIT. Absolute amount of solar radiation. 
A number of observations were made with the electrical com- 
pensation-pyrheliometer of ANGsTRÖM on different dates and also 
on the date of the eclipse, but the great variability of the weather 
and the continual high percentage of aqueous vapour in the atmo- 
sphere are the reasons why the western coast of Sumatra is a very 
unfavourable region for obtaining good series of observations of 
absolute solar radiation. 
The number of gram-calories per minute per square cm. on May 
18 at 105 45m a. m. was | 
Or ane. 
Very seldom a larger value than this was found during any of 
the days preceding the eclipse; only once we found 1,35. 
At Teneriffe, at a small elevation above the level of the sea 
Anestrom found Q = 1,37, the sun’s altitude being 70°. It appears 
therefore that even on clear days in the coast-region where we 
stayed the heat-radiation is to a considerable extent absorbed by 
the atmosphere. 
We intended to make observations with the pyrheliometer during 
the partial phase of the eclipse so long as the heat-radiation would 
be sufficiently intense, in order to check the simultaneous results 
of the thermopile, and to convert these latter into absolute measure. 
This end has however not been attained; owing to the exceeding 
variability of the radiation the pyrheliometer ceased to give reliable 
results soon after first contract. 
D. Amateur observations. 
The „Directions for amateur observers” contained a recommenda- 
tion for the following operations: 
I drawings of the corona; 
II photographs of the corona; 
III photographs of the landscape during the different phases of 
the eclipse ; 
IV observations of ,shadowbands” ; 
V meteorological observations ; 
VI further observations about : 
a the colour of the corona; 
b the visibility of the corona before and after totality ; 
c the colour of landscape and sky; 
d the visibility of stars. 
