( <48 ) 
fcrence between the true and vifible Place) vanifhes. 
But if Light be propagated in Time (which I prefume 
will readily be allowed by mod of the Philofophers 
of this Age) then itr is evident from the foregoing 
Confiderations, that there will be always a Difference 
between the real and vifible Place of an Object, un- 
lefs the Eye is moving either direddy towards or from 
• the Objed:. And in all Cafes, the Sine of the Dif- 
ference between the real and vifible Place of the Ob- 
jed:, will be to the Sine of the vifible Inclination of 
the Objed: to the Line in which the Eye is moving, 
as the Velocity of the Eye to the Velocity of 
Light. 
If Light moved but 1000 times fader than the Eye, 
and an Objed (fuppofed to be at an infinite Didance) 
was really placed perpendicularly over the Plain in 
which the Eye is moving, it follows from what hath 
been already laid, that the apparent Place of fuch an 
Objed will be always inclined to that Plain, in an 
Angle of 89° 56^; fo that it will condantly appear 
3 ; f from its true Place, and leem fo much lefs inclin- 
ed ro the Plain, that way towards which the Eye tends. 
That is, if AC is to A B (or AD) as 1000 to one, 
the Angle AB C will be 89° 5 ; 6 ' »,and ACB = 3' 4, and 
BCD = i ACB=7'. So that according to this Sup- 
pofition, the vifible or apparent Place of the Objed 
will be altered 7', if the Diredion of the Eye’s Mo- 
tion is at one time contrary to what it is at ano- 
ther. 
If the Earth revolve round the Sun annually, and 
the Velocity of Light were to the Velocity of the 
Earth’s Motion in its Orbit (which I will at prefent 
fuppofe to be a Circle) as 1000 to one ; then tis eafy 
to 
