[ '5 ]’ 
groffer exhalations, or fuch tranfient and; perishable 
materials. This hypothecs had at. leaft the air of 
being fupported by a very plaufible analogy. The 
minds of men being carried away by fuch prepof*’ 
feflions, it would lels 1 readily occur, that fuccefsful 
obfervations were only to be made, by an accurate 
and critical attention to thofe minute' changes, 
which the Ipots fometimes undergo. But what 
would ftill more conduce to this overlight, was 
the method, which moll of them followed, in mak- 
ing their obfervations. This was by the camera ob- 
fcura, which both scheiner and hevelius of- 
ten ufed, and which we find greatly extolled by 
them, and defcribed at great length in their 
writings. But fpots, when leen in this way, have 
nothing of that diftinflnefs, which is fo remark- 
able, and fo'plealing, when they are viewed direftly 
through a good telefcope armed with an heliofcope 3 > 
or glals properly fmoaked, , 
O’K \' d 
> p 11] ' ; - 
H.! ’PART 
