The English works of Thomas Hobbes of Malmesbury, Volume 01 (of 11) — Thomas Hobbes — John Shaqi
The English works of Thomas Hobbes of Malmesbury, Volume 01 (of 11)
Thomas Hobbes · en
Coroll. I. Lengths transmitted with motion so accelerated, that the
impetus increase continually in duplicate proportion to that of their
times, if the base represent the impetus, are in triplicate proportion
of their impetus acquired in the last point of their times. For as the
length D E is to the length D P, so is the parallelogram A M to the
parallelogram A N, and so the parabola A K I B to the parabola A K F.
But the proportion of the parabola A K I B to the parabola A K F is
triplicate to the proportion which the base B I has to the base F K.
Wherefore also the proportion of D E to D P is triplicate to that of B I
to F K.
Coroll. II. Lengths transmitted in equal times succeeding one another
from the beginning, by motion so accelerated, that the proportion of the
impetus be duplicate to the proportion of the times, are to one another
as the differences of cubic numbers beginning at unity, that is as 7,
19, 37, &c. For if in the first time the length transmitted be as 1, the
length at the end of the second time will be as 8, at the end of the
third time as 27, and at the end of the fourth time as 64, &c.; which
are cubic numbers, whose differences are 7, 19, 37, &c.
Coroll. III. In motion so accelerated, as that the length transmitted be
always to the length transmitted in duplicate proportion to their times,
the length uniformly transmitted in the whole time, and with impetus all
the way equal to that which is last acquired, is as a parabola to a
parallelogram of the same altitude and base, that is, as 2 to 3. For the
parabola A K I B is the impetus increasing in the time A B; and the
parallelogram A I is the greatest uniform impetus multiplied into the
same time A B. Wherefore the lengths transmitted will be as a parabola
to a parallelogram, &c., that is, as 2 to 3.
5. If I should proceed to the explication of such motions as are made by
impetus increasing in proportion triplicate, quadruplicate,
quintuplicate, &c., to that of their times, it would be a labour
infinite and unnecessary. For by the same method by which I have
computed such lengths, as are transmitted with impetus increasing in
single and duplicate proportion, any man may compute such as are
transmitted with impetus increasing in triplicate, quadruplicate, or
what other proportion he pleases.
In making which computation he shall find, that where the impetus
increase in proportion triplicate to that of the times, there the whole
velocity will be designed by the first parabolaster (of which see the
next chapter); and the lengths transmitted will be in proportion
quadruplicate to that of the times. And in like manner, where the
impetus increase in quadruplicate proportion to that of the times, that
there the whole velocity will be designed by the second parabolaster,
and the lengths transmitted will be in quintuplicate proportion to that
of the times; and so on continually.