C 21 9 ] 
eminence, in this, as well as in all other branches, 
placed their principal glory, no lefs in communi- 
cating knowledge, than in acquiring, or feeming to 
poffefs it; and were content to dedicate large por- 
tions of their time, to the removing of thofe diffi- 
culties for others, which they had once furmounted 
for themfelves. It is true, that in the variety of 
mathematical difeuffions, there are fome of fuch a 
nature, that it would be a defperate attempt to ren- 
der them intelligible to any but mathematicians ; to 
thofe, who to the natural faculty of combining, have 
added the mechanical and acquired habits of analytic 
calculation. Such fubjedts are bed treated with 
fcientific brevity. But this is no reafon for wrap- 
ping up others in a fimilar ftile ; and I mud obferve, 
that conclujionsy at lead, are always fufceptible of 
Ample perfpicuous expofition, however abftrufe the 
mode of invedigation, in fome cafes, may ne- 
ceflarily be, by which they are brought out. 
Such, sir, is the general fcope and plan of the 
following piece, which is prefented to you, in tedi- 
mony of the author’s relpeft and gratitude. 
I have the honour to be, sir, 
your much obliged, 
and mod obedient fervant. 
Temple, 
Nov. t8, 1773. 
SAMUEL HORSLEY. 
Ff a 
SEC- 
