SIR WILLIAM HERSCHEL 121 



the great counteraction of the united attractive force of whole sidereal 

 systems, which must be continually exerting their power on the par- 

 ticles while they are endeavouring to fly off. However, we shall 

 lay no stress on a surmise of this kind, as the means of verifying it 

 are wanting ; nor is it of any immediate consequence to us to know 

 the origin of the luminous matter. Let it suflice, that its existence is 

 rendered evident, by means of nebulous stars. 



