Galilei, Galileo - Mechanics

Galilei, Galileo, Mechanics, 1665

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Annotations of Dominico Mantovani upon the Bal-
lance of Signore Galileo Galilei.

Firſt, I conceive that the difficulty of Numbring the Wyres
is removed by wrapping about the Ballance ten of Steel,
and then ten of Braſs, which being divided by tens, there
only remains that tenth part to be numbred, in which the term
of the Mixt Metal falleth. For although Signore Galileo, who is
Author of this Invention, makes mention of two Wyres, one of
Steel, the other of Braſs, yet he doth not ſay, that we are to
take ^{*} ten of the one, and ten of the other: which it may be

hapneth by the negligence of him that hath tranſcribed it; al-
though I muſt confeſs that the Copy which came to my hands was
of his own writing.

* Galileus ſaith it
expreſly in this
Copy which I fol-
low, but might
omit it in the Co-
py which came to
the hands of Man-
tovani.

Secondly, it is ſuppoſed in this Problem that the Compoſition
of two Metals do retain the ſame proportion of Maſs in the
Mixture as the two Simple Metals, of which it is compounded,
had at firſt. I mean, that the Simple Metals retain and keep in
the Compoſition (after that they are incorporated and commix-
ed) the ſame proportion in Maſs that the Simple Metals had
when they were ſeparated: Which in the Caſe of Signore Gali-
leo, touching the Commixtion of Gold and Silver, I do neither
deny, nor particularly confeſs. But if one would, for example,
unite 101 pounds of Copper with 21 pounds of Tin, to make
thereof 120 pounds of Bell-Metal, (I abate two pounds,
ſuppoſed to be waſted in the Melting) I do think that 120
pounds of Compound Metal will have a leſs Bulk than the 100
pounds of pure Copper, and the 20 pounds of Tin unmixt, that
is, before they were incorporated and melted into one Maſs, and
that the Compoſition is more grave in Specie than the ſingle Cop-
per, and the ſingle Braſs: and in the Caſe of Signore Galileo the
Compoſition of Gold and Silver is ſuppoſed to be lighter in Specie
than the pure Gold, and heavier in Specie than the pure Silver. Of
which it would be eaſie to make ſome ſuch like experiment, melt-
ing together, v. gr. 10 pounds of Lead with 5 pounds of Tin,
and obſerving whether thoſe 15 pounds, or whatever the Mixture
maketh, do give the difference betwixt the weight in the Water
to the weight in the Air, in the proportion that the 15 pounds of
the two Metals diſ-united gave before: I do not ſay, the ſame diffe-
rence, becauſe I pre ſuppoſe that they will waſte in melting down,
and that the Compound will be leſs than 15 pounds, therefore I
ſay in proportion.

Thirdly, He doth alſo ſuppoſe, that one ought to take the

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