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t . , . 
Received June 5, 1766. 
XXVI. A Letter to the Prefident of the 
Royal Society , containing a new Manner of 
measuring the V elocity of Wind , and an 
Experiment to afcertain to what Quantity 
of Water a Fall of S?iow is equal . 
My Lord, 
Kirknewton, May 13, 1766. 
I<cad June ig, T Should think myfelf mod: unworthy of 
A the honour which your lordfhip and the 
Royal Society have done me, if the notice which you 
was pleafed to take of my letter upon the late comet, 
did not make me more careful to obferve whatever, I 
thought, might tend to improve the knowledge of 
nature, which is a capital part of the laudable delign 
of the Society. 
Your lordfhip knows, that my lituation expofes me 
to every blaffc that blows, and affords a fair opportunity 
for meafuring the velocity of the wind (the force of 
which I am, fo often, obliged to feel). I have attempt- 
ed to determine this by letting light downy feathers 
fly in the wind (the method, I underftand, ufed by 
the ingenious Dr. Derham); but cannot fay, in all the 
trials I have made (though I have let fifty of thefe 
feathers fly, one after the other, at a time), that I have 
ever feen above one, or two at moll, upon which I 
could have founded a calculation. The velocity of the 
wind near the earth is very unequal, upon account of 
the 
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