
CUBIC MEASURE. 85 
THE INSCRIBED SQUARE RULE. 
This rule gives the cubic contents of square pieces which can 
be exactly inscribed in cylinders of different sizes. The width of 
this square piece is usually obtained by multiplying the diameter 
of the cylinder by 17 and dividing the result by 24, or by multi- 
plying the diameter by 0.7071. This rule of thumb for calculat- 
ing the width of the inscribed square piece is based on the fact 
that one side of the square inscribed ina circle 24 inches in diam- 
eter is 17 inches long. 
The exact mathematical rule for determining the side of a 
square inscribed in a circle is to square the diameter, divide by 2, 
and extract the square root. The table following was computed 
by this method. | 
Practically the same results are obtained by the Seventeen-inch 
Rule, which is based on the fact that a 17-inch log will square 12 
inches. According to the Seventeen-inch Rule the cubic contents 
of a log are obtained as follows: Multiply the square of the diam- 
eter of the log by its length and divide by the square of 17. 
