314000. parts (for fo mmy Secmds there ZYt in po,l)egrees^ 
either in placing it , or inobferving , he (hall not miftake the 
thicknefs of a ffngle thred of Silk ^ He adds , that Great Inftm- 
ments have their defers, as the fmall ones : Forinthdfe, that 
are MovMe 5 if the thred, on which the Lead hangs, is any thing 
big 5 it cannot tX2i£t\y mzxk Seconds t, it be very fine , it breaks, 
becaufe of its great length ^ and the weight of the Lead : And in 
theJ'/Wooes, the greater the D/^wfifr is 5 the lefs the Shadow 
or the Light is terminated 5 fo that it is painful enough ^ exacftly to 
difcern the extremities thereof. Yet 'tis certain , that the greater 
the Inftruments are , thefurer Afironomers may be: Whence it is> 
tlm (omQ J (irommers have made ufe of obelisks of a vaft bignefs, 
to take the /^/mW^/ 5 and Signior o/jr/W, after the example of 
Bgmtk Dante ^ caufed a hole to be made on the. higheft part of 
a Wall of py . feet in a Church at Bononia , through which the 
beams of the Sun falling oat he Floor ^ mark as exadly as is pof- 
fible^ the height of that Luminary. 
Fifthly y That s.the Author reafons for the Immhility of the 
^^r/i^ after this manner. Hefuppofes for certain, that the Iwift- 
nefs of the Motion of heavy bodies dothftill increafe in their de- 
fcent^ to confirm which principle , he affirms to have experi- 
mented 3 That, if you let fall a Ball into one of the Scales of a 
Ballance , according to the proportion of the height , it falls from, 
it raifeth different weights in the other Scale, For example, A 
Wooden Ball ounce , falling from a height of 3 5 inches, 
raifeth a weight of 5. ounces 5 from the height of 140 inches , a 
W'eighi of 20 ounces 5 from that of 3 1 5 inches , one of 45 ouncesj 
and from another of 560 inches, one of §0 ounces, (^c^ From this 
principle he concludes the Earth to be at Reft 5 for , faith he, if it 
fliould have a Diurnal Motion upon its Center,Heavy Bodies being 
carried along with it by its motion , would indefcendingd'efcribea 
Curve Line , and , as he fliews by a Calculus j made by him 5 run 
equal fpaces in equal times 5 whence it follows, that the Celeri- 
ty of their Motion would not increafe in defcending , and that 
confequently their ftroke would not beftronger , after they had 
fallen thorow a longer fpace. 
UJ. ANA:: 
