[ 4 *] 
mercury funk a few degrees during the application of 
the coating, and the evaporation of the water; but 
prefently after rofe to 1 18°, or io° in confequence of 
the black coat with which I had covered that part of 
the bulb which was expofed to the Sun. If the bulbs 
of feveral correfponding thermometers were painted 
of different colours, and expofed at the fame time to 
the Sun, for a given period, fome conjectures, re- 
fpeCting the difpotition of the feveral primary colours 
for receiving and retaining heat, might he formed, 
which could not fail of being, in fome degree, in- 
terefting. 
I am, 
Dear Sir, 
Your mofl obedient fervant, 
Richard Watfon. 
Vol. LXIII. 
G 
VIII. A 
