320 
The Form of the Earth. [June, 
which is too exadt a science for them. The geometrician, 
however, knows his science is unassailable, and that no 
opinions or theories can controvert the fadts and laws with 
which he deals. 
Individuals who assert that the Earth is a flat surface 
bring forward the following as a proof that the known fadts 
can be accounted for thus : — They say the moon, for exam- 
ple, may appear 30° above the horizon and to the south 
of a person in 6o° N. lat. It may, at the same instant, 
appear in the Zenith of a person at the Equator ; and it 
may, at the same instant, appear 30° above the horizon and 
to the north of a person in 6o° S. lat. But, say these 
persons, these fadts do not in the least indicate that the 
Earth is round, because these changes can all be accounted 
for if the Earth is flat ; and they give the following as an 
example : — 
M 
Suppose M the moon, a e b a portion of the Earth and a 
flat surface ; A a locality 6o° north, E the Equator, b a 
locality 6o° south. 
The Moon as seen from A will have an altitude of e a m, 
say 30° ; at e the Moon will be in the Zenith ; at b the 
Moon will have an altitude of ebm, = 30°. Therefore, 
say these individuals, the fadt of the Moon being at different 
altitudes is no proof of the Earth being spherical in form. 
Geometry now comes to our aid to prove that a certain 
result would follow if the Earth were a flat surface, which 
it is known does not occur. The line M e would represent 
the sine of the angles mae,mbe, whilst A M and b m each 
represents the radius. Consequently, as the angles M a e 
and M b e are each 30°, the sine m e is equal to half M a or 
M B. Consequently the Moon seen from A or B would be at 
double the distance from either of these stations that it is 
from e. Consequently the Moon would appear to an ob- 
server, at E, to have twice the diameter that it would appear 
to have if seen from b, or a. 
