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refts, and a fmall nut at /, to prevent it from being blown 
off the fpindle by the wind. The whole inftrument is 
eafily turned round upon the fpindle by the wind, fo as 
alw^ays to prefent the mouth of the kneed tube towards 
it. The end of the fpindle has a fcrew on it; by which 
it may be fere wed into the top of a poft, or a ftand made 
on purpofe. It alfo has a hole at l, to admit a fmall le- 
ver for ferewing it into "wood w'ith more readinefs and 
facility. A thin plate of brafs k is foldered to the kneed 
tube, about half an inch above the round hole G, fo as 
, to prevent rain from falling into it. There is likewife a 
crooked tube ab (fig. 2.), to be put on occafionally upon 
the mouth of the kneed tube F, in order to prevent rain 
from being blowm into the mouth of the wind-gage, 
\vhen it is left out all night, or expoled in the time of 
rain. The force or momentum of the wind may be 
afeertained by the afliffance of this inftrument, by filling 
the tubes half-full of water, and pufliing the fcale a 
little up or down, till the o of the fcale, when the in- 
ftrument is held up perpendicularly, be on a line with 
the furface of the w^ater, in both legs of the wind-gage. 
The inftrument being thus adjufted, hold it up perpen- 
dicularly, and turning the mouth of the kneed tube to- 
W'ards the wind, ubferve how much the wat^r is depreffed 
by it in the one leg^ and how much it is raifed in the 
other. The fum of the two is the height of a column 
of water which the wind is capable of fuftaining at tliat 
time ; and every body that is oppofed to that wind, will 
be preffed upon by a force equal to the weight of a co- 
lumn 
