Salusbury, Thomas, Mathematical collections and translations (Tome I), 1667

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1poſſible that the Weight A ſhould be raiſed to D, although ſlow­
ly, unleſſe the other Weight B do move to E ſwiftly, it will not
be ſtrange, or inconſiſtent with the Order of Nature, that the
Velocity of the Motion of the Grave B, do compenſate the greater
Reſiſtance of the Weight A, ſo long as it moveth ſlowly to D,
and the other deſcendeth ſwiftly to E, and ſo on the contrary,
the Weight A being placed in the point D, and the other B in
the point E, it will not be unreaſonable that that falling leaſurely
to A, ſhould be able to raiſe the other haſtily to B, recovering by
its Gravity what it had loſt by it's Tardity of Motion.
And by
this Diſcourſe we may come to know how the Velocity of the
Motion is able to encreaſe Moment in the Moveable, according to
that ſame proportion by which the ſaid Velocity of the Motion is
augmented.
There is alſo another thing, before we proceed any farther, to
be confidered; and this is touching the Diſtances, whereat, or
wherein Weights do hang: for it much imports how we are to
underſtand Diſtances equall, and unequall; and, in ſum, in what
manner they ought to be mea­

ſured: for that A B being the
Right Line, and two equall
Weights being ſuſpended at
the very ends thereof, the point
C being taken in the midſt of
the ſaid Line, there ſhall be an
Equilibrium upon the ſame:
And the reaſon is for that the
Diſtance C B is equal to C A.
But if elevating the Line C B, moving it about the point C, it
ſhall be transferred into CD, ſo that the Ballance ſtand according
to the two Lines A C, and C D, the two equall Weights hanging
at the Terms A and D, ſhall no longer weigh equally on that
point C, becauſe the diſtance of the Weight placed in D, is made
leſſe then it was when it hanged in B.
For if we confider the Lines,
along [or by] which the ſaid Graves make their Impulſe, and
would deſcend, in caſe they were freely moved, there is no doubt
but that they would make or deſcribe the Lines A G, D F, B H:
Therefore the Weight hanging on the point D, maketh it's Moment
and Impetus according to the Line D F: but when it hanged in
B, it made Impetus in the Line B H: and becauſe the Line D F is
nearer to the Fulciment C, then is the Line B H Therefore we
are to underſtand that the Weights hanging on the points A and D,
are not equi-diſtant from the point C, as they be when they are
conſtituted according to their Right Line A C B: And laſtly,
we are to take notice, that the Diſtance is to be meaſured by