88 2>. HiftSCMfiL’s ObfervatloM, &c. 
fytng it are wanting s nor is it of any immediate confequence 
to us to know the origin of the luminous matter. Let it fuf- 
fiee, that its exiftence is rendered evident, by means of nebu* 
lous liars. 
I hope it will be found, that in what has been faid I have 
not launched out into hypothetical reafonings } and that faXs 
have all ajqng been kept fufflciently in view. But, in order to 
give every one a fair opportunity to follow me in the reflexions 
I have been led into, the place of every objeX from which I 
have argued has been purpofely added, that the validity of 
what I have advanced might he put to the proof by thofe who 
are inclined, and furnilhed, with the neceflary inftruments to 
undertake an attentive and repeated infpeXion of the fame 
phenomena, 
W. HERSCHEL. 
giemgh, Jan. i, 1791, 
