202 Mr. Powell's experimental enquiry ^ ^c. 
and being a solid mass compared with the thin bulb, is slower 
in acquiring heat, and therefore cools it, thus increasing the 
apparent effect on the other. 
( so. ) In a variety of other experiments which I have tried, 
using either this “ photometer," or another having the bulbs 
at equal heights, various apparent anomalies presented them- 
selves, all which I found easily explained on the principles 
here established of two radiations, when connected with the 
various other considerations to which it is necessary to refer 
when employing instruments of this description ; but I do 
not conceive it necessary to enter into* any further details. 
si 
From the Press of 
JF. NICOL, 
Cleveland-row, St. James's, London. 
