Archimedes Texts

227
downwards, and also forwards or backwards ten or fifteen fathom,
keeping it all the while parallel to its self, the visive ray cannot
stray from the point observed in the object, more than those fif
teen fathom; and because in a distance of eight or ten miles, the
Instrument takes in a much greater space than the Gally or other
Vessel kenn'd; therefore that small mutation shall not make me
lose sight of her. The impediment therefore, and the cause of
losing the object cannot befall us, unlesse upon the mutation made
angularly; since that Telescopes transportation higher or lower, to
the right, or to the left, by the agitation of the ship, cannot import
any great number of fathomes. Now suppose that you had two
Telescopes fixed, one at the Partners close by the Deck, and the o
ther at the round top, nay at the main top, or main top-gallant
top, where you hang forth the Pennon or streamer, and that they
be both directed to the Vessel that is ten miles off, tell me, whe
ther you believe that any agitation of the ship, & inclination of the
Mast, can make greater changes, as to the angle, in the higher tube,
than in the lower? One wave arising, the prow will make the main
top give back fifteen or twenty fathom more than the foot of the
Mast, and it shall carry the upper tube along with it so greata space,
& the lower it may be not a palm; but the angle shall change in one
Instrument aswell as in the other; and likewise a side-billow shall
bear the higher tube an hundred times as far to the Larboard or
Starboard, as it will the other below; but the angles change not at
all, or else alter both alike. But the mutation to the right hand or
left, forwards or backwards, upwards or downwards, bringeth no
sensible impediment in the kenning of objects remote, though the
alteration of the angle maketh great change therein; Therefore it
must of necessity be confessed, that the use of the Telescope on the
round top is no more difficult than upon the Deck at the Partners;
seeing that the angular mutations are alike in both places.

SALV. How much circumspection is there to be used in affirming
or denying a proposition? I say again, thar hearing it resolutely affir
med, that there is a greater motion made on the Masts top, than at
its partners, every one will perswade himself, that the use of the Te
lescope is much more difficult above than below. And thus also I w
ill excuse those Philosophers, who grow impatient and fly out into
passion against such as will not grant them, that that Cannon bullet
which they cleerly see to fall in a right line perpendicularly, doth
absolutely move in that manner; but will have its motion to be by
an arch, and also very much inclined and transversal: but let us
leave them in these labyrinths, and let us hear the other objections,
that our Author in hand brings against Copernicus.

SIMP. The Author goeth on to demonstrate that in the Do
ctrine of Copernicus, it is requisite to deny the Senses, and the