The English works of Thomas Hobbes of Malmesbury, Volume 07 (of 11)
Thomas Hobbes · en
But I return to your conclusion, that the excess of the proportion of
the increasing quantities above the third part of so many times the
greatest, decreaseth, as (1)/(6) (1)/(12) (1)/(18) (1)/(24) (1)/(30),
&c. For by this account in this row (0 + 1)/(1 + 1) = (1)/(2) where the
quantity above exceeds the third part of the quantities below by
(1)/(3), you make (1)/(3) equal to (1)/(6), which you do not mean. It
may be said your meaning is, that the proportion of 1 to the subtriple
of 2 which is (2)/(3), exceedeth what? I cannot imagine what, nor
proceed further where the terms be but two. Let us therefore take the
second row, that is, (0 + 1 + 4)/(4 + 4 + 4) = (5)/(12). The sum above
is 5, the sum below is 12, the third part whereof is 4; if you mean,
that the proportion of 5 to 4 exceeds the proportion of 4 to 12 (which
is subtriple) by (1)/(12), you are out again. For 5 exceeds 4 by unity,
which is (12)/(12). I do not think you will own such an equation as
(12)/(12) = (1)/(12) Therefore I believe you mean (and your next
proposition assures me of it), that the proportion of 5 to 4 exceeds
subtriple proportion by the proportion of 1 to 12; if you do so, you are
yet deceived.
For if the proportion of 5 to 4 exceeds subtriple proportion by the
proportion of 1 to 12, then subtriple proportion, that is, of 4 to 12
added to the proportion of 1 to 12 must make the proportion of 5 to 4.
But if you look on these quantities, 4, 12, 144, you will see, and must
not dissemble, that the proportion of 4 to 12 is subtriple, and the
proportion of 12 to 144 is the same with that of 1 to 12. Therefore by
your assertion it must be as 5 to 4 so 4 to 144, which you must not own.
And yet this is manifestly your meaning, as appeareth in these words:
“_Ut sit rationis provenientis excessus supra subtriplam ea quam habet
unitas ad sextuplum numeri terminorum post 0, adeoque_,” which cannot be
rendered in English, nor need to be. For you express yourself in the
twentieth proposition very clearly; I noted it only that you may be more
merciful hereafter to the stumblings of a hasty pen. For _excessus ea
quam_ does not well, nor is to be well excused by _subauditur ratio_.
Your twentieth proposition is this:
“_Si proponatur series quantitatum in duplicata ratione arithmetice
proportionalium (sive juxta seriem numerorum quadraticorum) continue
crescentium, a puncto vel 0 inchoatarum, ratio quam habet illa ad seriem
totidem maximæ æqualium subtriplam superabit; eritque excessus ea ratio
quam habet unitas ad sextuplum numeri terminorum post 0, sive quam habet
radix quadratica termini primi post 0 ad sextuplum radicis quadraticæ
termini maximi._”