134 Experimental Philosophy. [Lecture 10. 



it would hurt neither the man nor the animal. 

 It is the velocity, the swiftness, with which it is 

 impelled by the force of the powder, that enables 

 it to penetrate solid substances. Now it has been 

 demonstrated that light moves at least two millions 

 of times faster than a cannon-ball; and conse- 

 quently if the particles of light were only equal 

 in size to the two millionth part of a grain of sand, 

 we should be no more able to withstand their 

 force than we should that of sand shot point 

 blank from the mouth of a cannon. How in- 

 finitely small must these then be, when it is more 

 than probable they are not equal to a twentieth 

 that size, that is, not equal to theforty millionth 

 part of a grain of sand ! What an idea does this 

 give us of the works of our infinite Creator, and 

 how little must we seem in our own eyes ! O Phi- 

 losophy, how is it that thou dost not always teach 

 mankind humility ! 



But we have other proofs not less decisive than 

 this, of the extreme minuteness of the particles 

 of light. When we observe with what facility 

 they penetrate the hardest bodies, glass, crystal, 

 precious stones, and even the diamond itself, 

 through all which they find an easy passage, or 

 those bodies could not be transparent, How ex- 

 tremely small must these particles be ! When a 

 candle is lighted, if there is no obstacle to ob- 

 struct its rays, it will fill a space of two miles 

 round with luminous particles in an instant of 

 time, and before the least sensible part of the 



