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

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1ball ſuſpend it ſelf in its range directly over the Piece. And in a
word, if you do but attentively conſider, you will comprehend,
that the motion of the Earth in transferring the Piece along with
it from C A to E D, conferreth upon the tranſverſe line C D, ſo
much of little or great inclination, as is required to adjuſt the
range to its perpendicularity.
But you err, ſecondly, in that you
referr the faculty of carrying the ball along with the Earth to the
impulſe of the fire, and you run into the ſame error, into which
Salviatus, but even now ſeemed to have fallen; for the faculty
of following the motion of the Earth, is the primary and perpetual
motion, indelibly and inſeparably imparted to the ſaid ball, as to a
thing terreſtrial, and that of its own nature doth and ever ſhall
poſſeſs the ſame.
SALV. Let us yield, Simplicius, for the buſineſs is juſt as he

ſaith.
And now from this diſcourſe let us come to underſtand the
reaſon of a Venatorian Problem, of thoſe Fowlers who with their
guns ſhoot a bird flying; and becauſe I did imagine, that in regard
the bird flieth a great pace, therefore they ſhould aim their ſhot far
from the bird, anticipating its flight for a certain ſpace, and more
or leſs according to its velocity and the diſtance of the bird, that
ſo the bullet haſting directly to the mark aimed at, it might come
to arrive at the ſelf ſame time in the ſame point with its motion,
and the bird with its flight, and by that means one to encounter
the other: and asking one of them, if their practiſe was not ſo
to do; He told me, no; but that the ſlight was very eaſie and
certain, and that they took aim juſt in the ſame manner as if they
had ſhot at a bird that did ſit ſtill; that is, they made the flying
bird their mark, and by moving their fowling-piece they followed
her, keeping their aim ſtill full upon her, till ſuch time as they let
fly, and in this manner ſhot her as they did others ſitting ſtill.
It is
neceſſary therefore that that motion, though ſlow, which the
ing-piece maketh in turning and following after the flight of the
bird do communicate it ſelf to the bullet alſo, and that it be joyned
with that of the fire; ſo that the ball hath from the fire the
tion directly upwards, and from the concave Cylinder of the barrel
the declination according to the flight of the Bird, juſt as was ſaid
before of the ſhot of a Canon; where the ball receiveth from the
fire a virtue of mounting upwards towards the Zenith, and from
the motion of the Earth its winding towards the Eaſt, and of both
maketh a compound motion that followeth the courſe of the
Earth, and that to the beholder ſeemeth onely to go directly
wards, and return again downwards by the ſame line.
The
ing therefore of the gun continually directed towards the mark,
maketh the ſhoot hit right, and that you may keep your gun
rected to the mark, in caſe the mark ſtands ſtill, you muſt alſo hold