[ -73 ] 
XIV. A Paper to obviate fome Doubts concerning the great Mag- 
nifying Powers ufed . By Mr. Herfchel, F. R. S. 
TO SIR JOSEPH BANKS,. BART. P* R. S. 
SIR, 
1 HAVE the honour of laying before yon the refult of a fet 
of meafures I have taken in order to afcertain once more the 
powers of my Newtonian feven-feet reflector. The method I 
have formerly ufed, and which I hill prefer to that which I 
have now been obliged to praftife, requires very fine weather 
and a ftrong fun-lhiny day ; but my impatience to anfwer the 
requefts.of Sir Joseph banks would not permit me to wait for 
fo precarious an opportunity at this fe a foil of the year. The 
difference in all the powers, as far as 2010, will be found to 
be in favour of thole I have mentioned ; and, I believe, a 
much greater concurrence could not well be expe&ed, where 
different 
