[ 420 ] 
it is equal to the force of motion in an iron ball of 
a foot diameter moving ^ x ~ xvix th of ~ 1000 yards in 
i ' r , or to that of an iron ball of linch diameter moving 
th ^ 
f—, of i yard in 1 // , or to that of an iron ball of 
874679 XXI 1 
I of an inch diameter moving of 1 yard in 
1" t that is, moving lefs than — of 1 foot in 1"; 
. __ 4555 XXI 
that is, moving lefs than a foot in 4555 xx.i feconds, 
or in more than one hundred forty Jour thoufand 
milltojis of millions of Egyptian years : or the force 
of motion in each particle of light coming from the 
fun, is lefs than that in an iron ball of | of an inch 
diameter, moving at the rate of lefs than an inch in 
12 thoufand millions of millions of Egyptian years. 
Dr. Franklin’s firft queflion is anfwered. A par- 
ticle of matter, which is probably larger than any 
particle of light, moving with the velocity of light, 
has a force of motion, which, inftead of exceed- 
ing the force of a twenty-four pounder difcharged 
from a cannon, is infinitely lefs than that of the 
fmallefi: (hot difcharged from a pocket piftol, or lefs 
than any that art can create. 
I proceed to the other queftions — And, I think 
that 1 fhall make it appear, that it is very pofiibie 
that light may be produced by a continual emiffion 
of matter from the fun, without any fuch wafte of 
his fubftance as lhould fenfibly contract his dimen- 
fions, or fenfibly alter the motions of the planets, 
within any moderate length of time. 
Indeed, I do not think it neceflary to the produc- 
tion of any of the phenomena of light, that the 
emanation 
