C 68 ) 
V. A Propofition of General Vfe in the Art of 
Gunnery J Jhewing the Rule of Laying a Mor-- 
tar to pajiy in order to jlrike any ObjeSl abom 
or below the Horizon. By E. Halley. 
¥T was formerly the Opinion of thofe concerned in 
I Artillery, that there was a certain requifite of Pow- 
der for each Gun, and that in Mortars, where the Di- 
ftance was to Le varied, it muft be done by giving a 
greater or lefler Elevation to the Piece. But now our 
later Experience has taught us that the fame thing may 
be more certainly and readily performed by increafing 
and diminifliing the quantity of Powder, whether re- 
gard be had to the Execution to be done, or to the 
Charge of doing it. For when Bombs are difcharged 
with great Elevations of the Mortar, they fall too Per- 
pendicular, and bury themfelves too deep in the Ground, 
to do all that damage they might, if they came more 
Oblique, and broke upon or near the Surface of the 
Earth which is a thing acknowledged by the befieged 
in all Towns, who unpave their Streets, to let the Bombs 
bury themfelves, and thereby ftifle the force of their 
Splinters. A Second Convenience is, that at the ex- 
tream Elevation, the Gunner is not obliged to be fo Cu- 
rious in the Direction of his Piece, but it will fuf- 
fice to be within a Degree or two of the truth ; whereas 
in the other Method of Shooting he ought to be very . 
curious. But a Third, and no lefs confiderable Advan- 
tage is, in the faving the King's Powder, which in fo great 
and fo numerous Difcharges, as we have lately feen, muft 
needs amount to a confiderable value. And for Sea- 
Mortars, it is fcarce Practicable otherwife to ule them, 
where the agitation of the Sea continually changes th 
direftion of the Mortar, and would render the Sho 
very 
