MORTARS.
Practical rules.
To find the Charge for a given Range at 45° elevation.
13 inch Mortar.—To the range, in yards, add half the range, multiply the sum by ·03 for the charge, in ounces.
10 inch Mortar.—When the range is under 1350 yards, add to the range 160, and multiply by ·02; and if the range is over 1350 yards, add one-fifth of the range, and multiply by ·02 for the charge, in ounces.
8 inch Mortar.—To the range, in yards, add 20, and the sum multiplied by ·015 will give the charge, in ounces.
5½ inch Mortar.—To the range in yards, add 150, and multiply by ·08, for the charge, in ounces.
4⅖ inch Mortar.—To the range in yards add 300, and multiply by ·06, for the charge, in drams.
To find the Time of flight, the range being given. Divide the square root of the range, in feet, by 4·5 for the time of flight, in seconds.
To find the Range, the Time of flight being given. Multiply the time of flight, in seconds, by 4·5, and square the product for the range, in feet.
To find the length of Fuze,[8] for a given range. Multiply the time of flight, in seconds, by ·22, for the 13, and 10 inch mortars, and by ·24 for 8, 5½, and 4⅖ inch mortars, for the length of fuze, in tenths.