A general treatise of artillery, or, Great ordnance writ in Italian by Tomaso Morretii ... ; translated into English, with notes thereupon, and some additions out of French for sea-gunners, by Sir Jonas Moore, Kt. ; with an appendix of artificial fire-works for war and delight, by Sir Abraham Dager ...

Example II.

Let it be granted or supposed, that a Mortar of 300, at the Elevation of 54 degrees, shoots the Bombe 760 Paces; if one should desire to know what Elevation one ought to give to the same to shoot the Bombe 550 Paces, you must work by the Golden Rule in this manner.

As 760 Paces give the Number proportio∣nal 9510, so 550 Paces will give its proportio∣nal Number.

Wherefore if you multiply the second 9510 by the third 550, and dividing the Product by the first 760, the Quotient will be 6882, which Number, if you seek it amongst the proportio∣nal Numbers in the Tables, and not finding it just, if you take its nearest, it shall be the num∣ber 6947, to which corresponds the degrees 68,

which shall be the Elevation, and which ought to be given to the Mortar of 300, to fall in the distance of 550 Paces, with the same Charge of the first, and that is as much as I esteem ne∣cessary for every Soldier as well as for a Gun∣ner, who intends to be serviceable for his Prince and Countrey.