1
ſheweth his diſtruſt of a Spherical Inſtrument compoſed by
chimedes hiſmelf to take the Suns ingreſſion into the
ſheweth his diſtruſt of a Spherical Inſtrument compoſed by
chimedes hiſmelf to take the Suns ingreſſion into the
If in the fixed
ſtars one ſhould
diſcover any
nual mutation, the
motion of the
Earth would be
undeniable.
ſtars one ſhould
diſcover any
nual mutation, the
motion of the
Earth would be
undeniable.
It is proved what
ſmall credit is to be
given to
mical Inſtruments
in minute
tions.
ſmall credit is to be
given to
mical Inſtruments
in minute
tions.
* Braceia Italian.
* Or Mill.
Ptolomy did not
truſt to an
ment made by
chimedes.
truſt to an
ment made by
chimedes.
Inſtruments of
Tycho made with
great expence.
Tycho made with
great expence.
SIMP. But if the Inſtruments be ſo ſuſpitious, and the
vations ſo dubious, how can we ever come to any certainty of
things, or free our ſelves from miſtakes? I have heard ſtrange
things of the Inſtruments of Tycho made with extraordinary coſt,
and of his ſingular diligence in obſervations.
vations ſo dubious, how can we ever come to any certainty of
things, or free our ſelves from miſtakes? I have heard ſtrange
things of the Inſtruments of Tycho made with extraordinary coſt,
and of his ſingular diligence in obſervations.
SALV. All this I grant you; but neither one nor other of
theſe is ſufficient to aſcertain us in a buſineſſe of this importance.
theſe is ſufficient to aſcertain us in a buſineſſe of this importance.
I deſire that we may make uſe of Inſtruments greater by far, and
by far certainer than thoſe of Tycho, made with a very ſmall
charge; the ſides of which are of 4. 6. 20. 30. and 50. miles, ſo
as that a degree is a mile broad, a minute prim. 50 ^{*} yards, a
ſecond but little leſſe than a yard, and in ſhort we may without
a farthing expence procure them of what bigneſſe we pleaſe. I
being in a Countrey Seat of mine near to Florence, did plainly
obſerve the Suns arrival at, and departure from the Summer
Solſtice, whilſt one Evening at the time of its going down it
peared upon the top of a Rock on the Mountains of Pictrapana,
about 60. miles from thence, leaving diſcovered of it a ſmall
ſtreak or filament towards the North, whoſe breadth was not
the hundredth part of its Diameter; and the following Evening
at the like ſetting, it ſhew'd ſuch another part of it, but notably
more ſmall, a neceſſary argument, that it had begun to recede
from the Tropick; and the regreſſion of the Sun from the firſt to
the ſecond obſervation, doth not import doubtleſſe a ſecond
nute in the Eaſt. The obſervation made afterwards with an
quiſite Teleſcope, and that multiplyeth the Diſcus of the Sun
more than a thouſand times, would prove eaſie, and with all
delightful. Now with ſuch an Inſtrument as this, I would have
obſervations to be made in the fixed ſtars, making uſe of ſome
of thoſe wherein the mutation ought to appear more
ous, ſuch as are (as hath already been declared) the more
mote from the Ecliptick, amongſt which the Harp a very great
ſtar, and near to the Pole of the Ecliptick, would be very
per in Countries far North, proceeding according to the
ner that I ſhall ſhew by and by, but in the uſe of another ſtar;
and I have already fancied to my ſelf a place very well adapted
for ſuch an obſervation. The place is an open Plane, upon
which towards the North there riſeth a very eminent Mountain,
in the apex or top whereof is built a little Chappel, ſituate Eaſt
and Weſt, ſo as that the ridg of its Roof may interſect at right
angles, the meridian of ſome building ſtanding in the Plane. I
will place a beam parallel to the ſaid ridg, or top of the Roof,