g0 ESSAYS anp OBSERVATIONS 
' 43. THE velocities of the red and vio- 
let in air, are, by the above eftimation, as 
78 and 77 *; and the intervals of their 
fits are, By experiment f, as too and 63: 
From whence, by the canon now laid 
down, the velocity of the ethereal pulfes 
is found to be to that of red light, as 
79753 to 78000. As light moves from 
the fun to us, by Dr Bradley’s lateft com- 
putation t, in 8’, 12”, the pulfés of the e- 
thereal fluid will be i > fia tabacyt 
the fame fpace in 8’, 1%. 
44. THE diftance between the ethereal 
pulfes is, to || the interval of the fits in 
red, as the difference between the velocity 
of the ethereal pulfes and that of red light 
as to the velocity of red light ; that inter- 
val, therefore, is not much more than ';th 
of 
C—v tov; therefore, ex aequo, 1 is to #a8 CV—Vz to » 
€v—Vv : From which arifes the equation — 
v g i— X Vo 
“TX 7X Vy 
* In the celeftial medium they are lefs, [No 40.7 but. 
very nearly in the fame proportion, 
tT Newt, opt. book 2. p. 1, obfervat, 14, 
t See Eames abridg- tranfa@: vol, vi. Ps 15:7. 
i See note * to foregoing page, 
