1885.] 
The Form of the Earth. 
321 
But the Moon, whether seen overhead from the Eauatnr 
pea 3 rs no^Talf tl ^ a l0Cality north or soa th, a p- 
“ hlf 16 dla 1 n J ete 1 r that ^ appeared at the Equator 
neaily as possible the same diameter. Therefore the 
assumption of the Earth being a flat surface is contrad^ed 
wn ^fq ai Q n ’ lf the Earth were a flat surface, an observer at a 
would see a crater at o in the centre of the Moon • whereas 
be on S Hi? W ° Uld n0t See this crater at all, a ^ it would 
? h . nearIy tde 0 PPosite side of the Moon to that which 
urfaof ^ u W ° Uld See ’ If > then ’ the Ear th were a flat 
Jp f ri , obser Y ers ln dlffer ent parts of the Earth would 
see a different portion of the Moon ; but such is not the 
that th C p°F Seq H ent y n Ge0metry proves that the assumption 
tha the Earth is a flat surface is erroneous. P 
Wow what are the conditions that must be fulfilled as 
follows 8 :— 6 M °° n When S6en fr ° m the Earth - The y are as 
A n observer m 6o° N. or S. latitude must see the Moon 
30 above his horizon, at the same instant that an 
observer at the Equator sees it at its Zenith. 
2. I he observer north and south of the Equator must find 
the diameter of the Moon of nearly the same value 
as it is to an observer at the Equator 
3. The three observers above named must'see exadtly the 
same face ” of the Moon. y 
diagram'?— ‘ heSe ^ We haVe the followi "g 
I. 
A, an observer north of the Equator, sees the same face 
01 m, the Moon, o as is seen by observers at e or b. 
I he moon, M, is vertical to an observer at e, and 30° above 
the horizon to the observers at a and b. 
The diameter of m, the Moon, will appear as nearly as 
possible of the same size to each observer at a, e and p 
because the difference in the Moon’s distance from these 
three points is very slight. 
Here, then, we have every known fa ft connected with the 
Moon explained by giving to the Earth a spherical form, 
