( 57* ) 
Limb is ftill above the Horizon about { of his Diame- 
ter, or 20 Minutes, upon the fcoreof the Refra&ion, 
and the height of the Eye of the Obferver above the 
Surface of the Sea: Orelfe they are to work the Am- 
plitudes as they do the Azimuth, reckoning the Sun's 
diftance from the Zenith 90° 36': This, tho it be of 
little confequence near the Equino&ial, will make a 
great error in high Latitudes, where the Sun rifes and 
lets obliquely. 
But to return to our Hypothefis, In order to explain 
the change of the Variations* we have adventured to 
make the Earth hollow and to place another Globe 
within it : and I doubt not but this will find Oppofers e- 
nough. I know 'twill be obje&ed, That there is no In- 
ftance in Nature of the like thing 5 That if there was 
fuch a middle Globe it would not keep its place in the 
Centre, but be apt to deviate there-from, and might 
poffibly chock againft the concave Shell, to the ruine 
or at leaft endammaging thereof , That the Water of 
the Sea would perpetually leak through, unlefs we fup- 
pofe the Cavity full of Water $ That were it poffible 
yet it does not appear of what ufe fuch an inward Sphere 
can be of, being (hut up in eternal Darknefs, and there- 
fore unfit for the Produ&ion of Animals or Plants 5 
with many more Obje&ions, according to the Fateof 
all fuch new Propofitions, 
To the(e, and all others that I can forefee,I briefly an- 
fwer. That the King environing the Globe of Saturn is 
a notable Inftance of this kind, as having the fame com- 
mon Centre, and moving along with the Planer, with- 
out fenfibly approaching him on one fide more than the 
other. And if this Ring were turned on one of its Dia- 
meters, it would then defcribe fuch a concave Sphere 
as I fuppofc our External one to be. And fince the Ring 
in any pofition given, would in the fame manner keep 
the Centre of Saturn in its own, it follows that fuch a 
concave 
