CHAP. XLII. (Book 42)
Of measuring Timber and other solid Bodies, with several Ta∣bles usefull thereunto, &c. (Book 42)
IN Board, Glass, Land, &c. we onely took notice of the Length and Breadth, which was sufficient to find the superficial Content; but to measure solid Bodies we must take notice of the Length, Breadth and Depth. Most of solid Figures are measured by finding first the superficial Content of the Base, or one End, and multiplying that by the Length, if both Ends alike; but if tapering, then by ⅓ of the Length; and as superficial Measure hath 144 square Inches in one foot, and 72 square Inches in half a foot, and 36 square Inches in a Quar∣ter: So
- In solid Measure 1728 square Inches make one foot,
- And 8.64 square Inches make half a foot,
- And 432 square Inches make a quarter of a foot.
For every Inch square is like a Die, and so is a foot of solid Measure supposed to be; for what it wants either in Breadth or in Thickness, it must have in Length; so that in what form soever your solid Body is, that you measure, there must be 1728 solid Inches to make a foot; for 12 (the side of a foot) multiplyed by 12 gives 144 for one side; and 144 multiplyed by 12 (another side) gives 1728, the Cube-square Inches in a Cube-square foot.
Now to find the solid Content of any piece of Timber or Stone that hath the sides equal, first find the superficial Content of the End, in