specific gravity of water be called 1000, the proportional specific
gravities of all other bodies will nearly express the number of
averdupois ounces in a cubic foot. Or more accurately, supposing the
specific gravity of water expressed by 1. and of all other bodies in
proportional numbers, as the cubic foot of water weighs, at the above
temperature, exactly 437489.4 grains Troy, and the cubic inch of water
253.175 grains, the absolute weight of a cubical foot or inch of any
body in Troy grains may be found by multiplying their specific gravity
by either of the above numbers respectively.
By Everard's experiment, and the proportions of the English and French
foot, as established by the Royal Society and French Academy of
Sciences, the following numbers are ascertained.
Paris grains in a Paris cube foot of water = 645511
English grains in a Paris cube foot of water = 529922
Paris grains in an English cube foot of water = 533247
English grains in an English cube foot of water = 437489.4
English grains in an English cube inch of water = 253.175
By an experiment of Picard with the measure and
weight of the Chatelet, the Paris cube foot of
water contains of Paris grains = 641326
By one of Du Hamel, made with great care = 641376
By Homberg = 641666
These show some uncertainty in measures or in weights; but the above
computation from Everard's experiment may be relied on, because the
comparison of the foot of England with that of France was made by the
joint labours of the Royal Society of London and the French Academy of
Sciences: It agrees likewise very nearly with the weight assigned by Mr
Lavoisier, 70 Paris pounds to the cubical foot of water.
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