Useful Tables for Draughtsmen.
The circle contains a greater area than any other plane figure bounded by an equal perimeter or outline.
TO FINDCIRCUMFERENCE—
TO FINDDIAMETER—
TO FINDRADIUS—
TO FIND SIDE OF AN INSCRIBEDSQUARE—
TO FIND SIDE OF AN EQUALSQUARE—
SQUARE—
TO FIND THE AREA OF ACIRCLE—
Contents of cylinder = area of end × length. Contents of wedge = area of base ×1⁄2altitude. Surface of cylinder = area of both ends × length × circumference. Surface of sphere = diameter squared × 3.1416, or = diameter × circumference. Contents of sphere = diameter cubed × .5236. Contents of pyramid or cone, right or oblique, regular or irregular = area of base ×1⁄3altitude. Area of triangle = base ×1⁄2altitude. Area of parallelogram = base × altitude. Area of trapezoid = altitude ×1⁄2the sum of parallel sides.
This is used in measuring bodies, or things having length, breadth and height or depth.
TABLE.
The circumference of every circle whatever, is supposed to be divided into 360 equal parts, calleddegrees.
A degree is1⁄360of the circumference of any circle, small or large.
A quadrant is a fourth of a circumference, or an arc of 90 degrees.
A degree is divided into 60 parts called minutes, expressed by the sign (′), and each minute is divided into 60 seconds, expressed by (″); so that the circumference of any circle contains 21,600 minutes, or 1,296,000 seconds.
The mile (5,280 feet) of the above table is the legal mile of the United States and England, and is called the statute mile.