MIcROGRAPHItA 
 Firft, From the irregular furface of the Moon, and ftom feveral Paral- 
laxes, that unlefs the Dichotomy happen in the Nonagefimus of the Eclip- 
tick, and that in the Meridian, ec. all which happen fo very feldom, 
. 
that it is almoft impoffible to make them otherwife then uncertainly. 
Befides, we are not yet certain, but that there may be fomewhat about 
the Moon azalogws to the Air about the Earth, which may caufe a refra- 
étion of the light of the Sun, and confequently makea great difference 
in the apparent dichotomy of the Moon. Their way indeed is very 
rational and ingenious ; and {uchasis much to be preferr'd before the 
way by the Horizontal Parallax, could all the uncertainties be remov'd, 
and were the true diftance of the Moon known. | | 
But becaufe we find by the Experiments of Vendiline, Reinoldws, &c: 
that Obfervations of this kind are very uncertain alfo? It were to be 
wifht, that fuch kind of Obfervations, made at two very diftant ftati- 
ons, were promoted. And it is fo much the more dchttistes ecaute, from 
_what I have now fhewn of the nature of the Air, itis evident, that the 
oat dhicn may be very much greater thenall the Aftronomers hitherto 
have imagined it: And confequently, that the diftance of the Moon, and 
other Planets, maybe much lefle then what they have hitherto made 
it, iad tom 
For firft, this Inflection, I have here propounded, will allow the fha- 
dow of the Earth to be much fhorter then it canbe made by the other 
Hypothefis of refraction, and confequently, the Moon will not fuffer an 
Eclipfe, unlefs it comes very much nearer the Earth then the Aftronomers 
hitherto have fuppofed it. — 
Secondly, There will not in this Hypothefis be any other fhadow of the 
: Earth, fuch as Kepler fuppofes, and calls the Penumbra, whichis the fha- 
dow of the refracting Atmofphere 5 for the bending of the Rays being al- 
. together caus’d by Inflection, as I have already thewn , all that part 
which is afcribed by Kepler, and others after him, to the Penumbra, or 
dark part, which is without the wbra terre, does clear vanifh 5 for in 
_ this Hypothefis there is no refracting furface of the Air, and confequently — 
there can be no fhadows, fuch as appear inthe ninth Figure of the 37. 
Scheme, where let ABC D reprefent the Earth, and EF GH the 4- 
mofphere;which according to Keplers fuppofition,is like a Sphere of Water 
terminated with an exact furface EF GH, let the lines MF, LB, ID, 
K H, reprefent the Rays of theSun; ’tismanifett, that all the Rayes be~ 
tween LB, and ID, will be reflected by the» furfaee of the Earth 
BAD, and confequently, the conical fpace BOD would be dark and 
obfcure; but, fay the followers of Kepler, the Rays between MF, vand 
LB, and between’ 1D, and K H, ‘falling on the Atmofphere , are re~ 
fracted, both at their ingrefs and e refs out of the Atmofphere, nearer to~ 
wards the Axis of the {perical fhadow CO, and confequently, inlighten® 
a great part of that former dark Cone, and fhorten, and contract, its top 
toN. And becaufe of this Reflection of thefe Rays, fay they, there 1s 
fuperinduc’d another fhell of a dark Cone F P H, who eApexP is yet 
further diftant from the Earth: By this Peewmbra, fay they, =r 
239 
