376 Scientific Proceedings, Royal Dublin Society. 
CoNcLUSION. 
It is apparent, from inspection of figure 4, that the curves 
do not coincide, even approximately. In fact the observations 
indicate that, at 35 22™ the moment of greatest phase, more light 
was received from the Sun than should have been theoretically in 
the ratio of 2°348 to 1:63. Itisdifficult to propound a satisfactory 
explanation of this inconsistency’ between theory and experi- 
ment. 
Experiments were made to test if the time of exposure of the 
actinometer used obeyed the “‘ Photographic Law,” and was really 
inversely proportional to the intensity. This was done by measur- 
ing the variation in actinic power of the light from an are lamp at 
different distances. 
If 
J, = the intensity of the light at unit distance 
and 
ile - a distance D, 
then 
I 
Ji ae 
D:? 
1 An inconsistency in the direction found would take place if the Sun’s disc were 
not uniformly intense, and if the edge were more powerful in actinic effect than the 
centre. This might be tested by taking an under-exposed photograph of the Sun, and 
would be verified if the edge of the Sun were more clearly defined than his centre. 
Also an error in the calculated distance of the Moon from the Earth making it less than 
it actually was, or the existence of an atmosphere on the Moon would tend to have the 
same effect. But none of them would cause a discrepancy of such magnitude as that 
observed. The eclipse was actually found to last some 5 seconds less than was expected 
in Spain. 
