36 
when there is wind the effect is masked, but I feel confident 
that by increasing the length of the tube, making it 30 feet 
for instance, and using certain precautions, this difficulty 
may be overcome. 
“On Solar Radiation,” by Joseph Baxendell, F.R.A.S. 
Although observations of solar radiation have now been 
regularly made for several years at various public observa- 
tories, and by many amateur meteorologists, I am not aware 
that any useful or important result has yet been deduced 
from them. It seems to be generally supposed that the 
disturbing influences which affect the indications of the 
black-bulb thermometer are so uncertain and irregular in 
their action as to render it almost hopeless to expect 
that any new and valuable result can be obtained from 
them. On comparing sets of observations made by different 
observers, the most startling and discouraging discrepancies 
are often found to exist, for which, in the absence of any 
information as to the exact circumstances under which the 
observations were made, it is impossible to account satis- 
factorily. A few years ago an enquiry in which I was 
engaged, led me to undertake a discussion of the Greenwich 
solar radiation observations ; but the results proved so per- 
plexingly anomalous and unsatisfactory, that I could not 
venture to place any reliance upon them. Having, however, 
recently become possessed, through the kindness of the 
Rev. Robert Main, F.R.S., and the Trustees of the Radcliffe 
Observatory, Oxford, of copies of the volumes of Radcliffe 
Observations for the years 1858 to 1864, and finding that 
they contained a valuable series of solar radiation observa- 
tions, I have been led to resume the subject, and although the 
enquiry is still incomplete, I have thought that some of the 
results already obtained are sufficiently curious and remark- 
able to render it desirable to bring them before the society, 
in order that attention may be drawn to a much neglected 
