[ 33 * ] 
cafe of a comparlfoii made betwixt the rpecurum- 
above-mentioned, and the brafs end or cover of the 
fame telefcope ; for the ice was found ftill to cleave 
to its furface a good while after the fpeculum was 
entirely cleared,. Thefe imperfeft experiments are- 
only mentioned by the bye, and may perhaps ferve as. 
hints toothers, who may be difpofed toprofecute this 
part of natural phiiofophy. 
Some particular reafons have occurred, which will 
hinder me from tranfmitting to you the paper on the; 
folar fpots, till fome time next winter, by which time 
I fliall have finifhed every thing 1 have to fay on 
that fubjedl., Widiing to hear from you at your 
leifurCj. I ever am, with much refpedt. 
Reverend Sir,, 
Your moft obedient fervant,. 
Alexander Wilfon^ 
Frofeffor of Agronomy at Glafgow:. 
Fu. z 
Receivedi 
