•14G M E U O IK S of the 
Troh. I. A fliot being made on an inclinecl plane, having the 
horizontal diftancc of the obje£t it ftrikes, with the elevation of 
the piece, and the angle at the gun, between the obie£t and the 
perpendicular 9 to find the greateft horizontal range of that piece, 
loaded with the fame charge ; that is, half the Latus Rectum of 
all the paraboliE made with the lame impetus. 
Take half the diflance of the objedt from the Nadir ^ and take 
the difference of the given elevation from that half; the veried 
fine of twice that difference, lubftracl from the vcrfed fine of the 
diflance of the objedt, from the zenith; then will the difference 
of thole verfed lines, be to the fine of the diftance of the obje^l 
from the zenith, as the horizontal diftance of the obje61 flruck to 
the greateft horizontal range, at 45°. 
'Proh. 2. Having the greateft horizontal range of a gun, the 
horizontal diflance, and angle of inclination of an obje6l to the 
perpendicular ; to find the two elevations neceflary to flrike that 
objefl. 
Halve the diflance of the obje£l from the Nadir -^ this half is 
always equal to the half fum of the two elevations fought ; then 
day, as the greateft horizontal range is to the horizontal diflance 
of the objedl, fo is the fine of the angle of inclination, or dif- 
tance of the obje6l from the perpendicular, to a fourth propor- 
tional ; which fourth being fubftra6led from the veried fine of ^ the 
diflance of the objefl from the zenith, leaves the verfed fine of 
the difference of the elevations fought; which elevations are 
therefore had, by adding or liabflradling that half difference to 
and from the abovefaid half fum. 
It only remains, by good and valid experiments, to be affured 
of the force of gun-powder; how to make and conferve it equal; 
and to know the efiFe(St thereof in each piece; that is how far dif- 
ferent charges will cafl the lame fhot; which may mofl conve- 
niently be ingraven on the outfide thereof, as a flanding direction 
to all gunners, who fhall from thenceforward have occafion to 
ufe that piece. And were this matter well afcertained, it might 
be worth the while to make all mortars of the like diameter, as 
near as poffible alike in length of chafe, weight, chamber, and 
all other circumftances. 
An Account o/Tadmor; by Mr. Will. Halifax. Phil. Tranf. 
N° 217. p. 83. 
FROM Aleppo to Tddmor are fix days eafy journey, over a 
defart country; as you ride into the town, there is a callle 
about half an hours diftance from ir, and ib fituated as to 
command 
