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

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1which likewiſe have for their Center that of the Earth, for that it
is not any way ſenſible.
The WEDGE, Cuneus.
The Force of the Wedge A B C D is eaſily underſtood after
that which hath been ſpoken above of the Inclined Plane,
for the Force wherewith we ſtrike downwards acts as if it
were to make it move according to the Line B D; and the Wood,
or other thing and Body that it cleaveth, openeth not, or the
Weight that it raiſeth doth not riſe, ſave only according to the

Line A C, inſomuch that the Force,
wherewith one driveth or ſtriketh this
Wedge, ought to have the ſame Pro­
portion to the Reſiſtance of this
Wood or Weight, that A C hath to
A B.
Or elſe again, to be exact, it
would be convenient that B D were
a part of a Circle, and A D and
C D two portions of Spirals that had the ſame Center with the
Earth, and that the Wedge were of a Matter ſo perfectly hard
and polite, and of ſo ſmall weight, as that any little Force would
ſuffice to move it.
The CRANE, or the CAPSTEN,
Axis in Peritrochio.
We ſee alſo very eaſily, that the Force wherewith the Wheel
A or Cogg B is turned, which make the Axis or Cylinder C
to move, about which a Chord is rolled, to which the
Weight D, which we would raiſe, is faſtned, ought to have the

ſame proportion to the ſaid
Weight, as the Circumference of
the Cylinder hath to the Cir­
cumference of a Circle which
that Force deſcribeth, or that the
Diameter of the one hath unto
the Diameter of the other; for
that the Circumferences have the
ſame proportion as the Diame­
ters: inſomuch that the Cylinder C, having no more but one foot
in Diameter, if the Wheel AB be ſix feet in its Diameter, and the
Weight D do weigh 600 pounds, it ſhall ſuffice that the Force in
B ſhall be capable to raiſe 100 pounds, and ſo of others.
One may