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EXAMPLE. 
If it were required to know the force of the wind, 
when the column of water fuftained was equal to 
inches. Then, by tab. i. 
Pounds. 
4 inches = 20,833^ 
o,5orYinch= 2,604 
0,1 = 0,521 
Sum 4,6= 23, 958 = force on every fquare foot^ 
Any change that can happen in the fpecific gravity 
of the water from heat or cold, will make no fen* 
lible alteration on experiments made with this inftru* 
ment. 
A cubic foot of water is generally fuppofed to weigh 
1000 Avoirdupois ounces; and from fome experiments 
made by Mr. musschenbroek it would appear, that be* 
Cwixt freezing and boiling, or in 1 80® on Fahrenheit’s 
fcale, it increafes only ^ = ,0117 of its whole bulk, or 
volume w. I cannot, however, find any author that men* 
dons at what precife degree of heat a cubic foot of water 
was weighed. Mr. Fahrenheit indeed made feveral of 
his curious experiments on the fpecific gravities of bo* 
dies when the water raifed his thermometer to ^S°cOi 
Now if we fuppofe the greatefi: heat of the water which 
(b) MUsscHEN. Introd. ad Philof. Natur. tom. II. p. 625. 
(c) Philofophical Tranfadions, N° 383. 
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