A man pulling a [dead] weight balanced against himself cannot pull
more than his own weight. And if he has to raise it he will [be able
to] raise as much more than his weight as his strength may be more
than that of other men. [Footnote 7: The stroke at the end of this
line finishes in the original in a sort of loop or flourish, and a
similar flourish occurs at the end of the previous passage written
on the same page. M. RAVAISSON regards these as numbers (compare the
photograph of page 30b in his edition of MS. A). He remarks: "_Ce
chiffre_ 8 _et, a la fin de l'alinea precedent, le chiffre_ 7 _sont,
dans le manuscrit, des renvois_."] The greatest force a man can
apply, with equal velocity and impetus, will be when he sets his
feet on one end of the balance [or lever] and then presses his
shoulders against some stable body. This will raise a weight at the
other end of the balance [lever], equal to his own weight and [added
to that] as much weight as he can carry on his shoulders.
384.
No animal can simply move [by its dead weight] a greater weight than
the sum of its own weight outside the centre of his fulcrum.
385.
A man who wants to send an arrow very far from the bow must be
standing entirely on one foot and raising the other so far from the
foot he stands on as to afford the requisite counterpoise to his
body which is thrown on the front foot. And he must not hold his arm
fully extended, and in order that he may be more able to bear the
strain he must hold a piece of wood which there is in all crossbows,
extending from the hand to the breast, and when he wishes to shoot
he suddenly leaps forward at the same instant and extends his arm
with the bow and releases the string. And if he dexterously does
every thing at once it will go a very long way.
386.
When two men are at the opposite ends of a plank that is balanced,
and if they are of equal weight, and if one of them wants to make a
leap into the air, then his leap will be made down from his end of
the plank and the man will never go up again but must remain in his
place till the man at the other end dashes up the board.
[Footnote: See Pl. XXIV, No. 3.]
387.
Of delivering a blow to the right or left.
[Footnote: Four sketches on Pl. XXIV, No. 1 belong to this passage.
The rest of the sketches and notes on that page are of a
miscellaneous nature.]
388.
Why an impetus is not spent at once [but diminishes] gradually in
some one direction? [Footnote 1: The paper has been damaged at the
end of line 1.] The impetus acquired in the line _a b c d_ is spent
in the line _d e_ but not so completely but that some of its force
remains in it and to this force is added the momentum in the line _d
e_ with the force of the motive power, and it must follow than the
impetus multiplied by the blow is greater that the simple impetus
produced by the momentum _d e_.
[Footnote 8: The sketch No. 2 on Pl. XXIV stands, in the original,
between lines 7 and 8. Compare also the sketches on Pl. LIV.] A man
who has to deal a great blow with his weapon prepares himself with
all his force on the opposite side to that where the spot is which
he is to hit; and this is because a body as it gains in velocity
gains in force against the object which impedes its motion.
On hair falling down in curls.
389.
Observe the motion of the surface of the water which resembles that
of hair, and has two motions, of which one goes on with the flow of
the surface, the other forms the lines of the eddies; thus the water
forms eddying whirlpools one part of which are due to the impetus of
the principal current and the other to the incidental motion and
return flow.
[Footnote: See Pl. XXV. Where also the text of this passage is given
in facsimile.]
On draperies (390--392).
390.