The arte of gunnerie. Wherein is set foorth a number of seruiceable secrets, and practical conclusions, belonging to the art of gunnerie, by arithmeticke skill to be accomplished: both pretie, pleasant, and profitable for all such as are professors of the same facultie. / Compiled by Thomas Smith of Barwicke vpon Tweed souldier.

To find out the superficies of any round body, as bullet, globe, &c. diuerse and sundry waies.

Question.

I haue a demy Cannon bullet of 7 inches diameter, I demaund how many inches the superficiall content therof is?

Resolution.

To answer this and all such like, I must in the order before shewed, find out the circūference of the bullet, and I find that a bullet of 7 inches diameter, shall cōtaine 22 inches in circūference, which circumference being multiplied in the diameter, ariseth 154 inches, the true number of inches contained vpon the superficies of a bullet of 7 inches diameter.

Another way.

Multiply the square of the diameter of any bullet or globe by 22/7 the product is your desire. Example: The bul∣let whose diameter was 7 inches being squared, the square thereof is 49, which multiplied by 22, yeelds 1078 which sum deuided by 7, the quotient is 154 inches as before.

Another way.

Deuide the square of the circumference of any bullet by 22/7 your quotient nūbers will shew you the superficiall measure of the same.

Example:

The circumference of the bullet aforenamed of 7 in∣ches diameter containeth 22 inches, the square thereof is 484 inches, that number deuided by 22/7 as you do in fra∣ctions, in setting an vnite vnder the square number thus, 484/1 and multiplying the said square number by the deno∣minator of the other fraction being 7, ariseth 3388, which deuided by the numerator 22, the quotient

is 154 inches, the superficiall content thereof, as before.