C 39' ] 
ther from the Eye when in the Horizon, than when it 
is fome Degrees high. Now when the Moon is at G, 
we confider it as at g, not much farther than G 5 but 
when it is at H, we imagine it to be at h, almoft as far 
again. Therefore, while it fubtends the fame Angle 
as it did before (nearly), we imagine it to be fo much 
bigger as the Diftance feems to us to be encreafed. 
I have contriv'd the following Experiment to illuf- 
trate this : Fig. y. 
I took two Candles of equal Height and Bignefs 
A B, CD, and having plac'd A B at the Diftance of 
fix or eight Feet from the Eye, I placed CD at double 
that Diftance j then caufing any unprejudic'd Perfon to 
look at the Candles, I ask'd which was biggeft l and 
the Spectator faid they were both of a Bignefs 5 and that 
they appear'd fo, becapfe he allow'd for the greater 
Diftance of C D 5 and this alfo appear'd to him, when 
he look'd thro' a fmall Hole. Then defiring him to 
(hut his Eyes for a Time, I took away the Candle CD, 
and plac'd the Candle E F clofe by the Candle A B,and 
tho' it was as fhort again as the others, and as little 
again in Diameter, the Spectator, when he open'd his 
Eyes, thought he faw the fame Candles as before., 
Whence it is to be concluded, that when an Ob- 
ject is thought to be twice as far from the Eye as 
it was before, we think it to be twice as big, tho 3 
it fubtends but the fame Angle.- — -And this is the 
Cafe of the Moon, which appears to us as big again* 
when we fuppofe it as far again, tho' it fubtends but 
the fame Angle. 
The Difference of Diftance of the Moon in Pa- 
ngeo and Apogeo, will account for the different 
BigneJ& 
