Area of column sq. inches X tons per inch corresponding to proportion of length, as per table above = Breaking weight, tons.

If the ends are rounded, divide the final result by 3 to find the breaking weight.

In columns of oblong section, the narrowest side must always be taken in calculating the proportion of height to width.

Square Ends.

Rounded or Movable Ends.

Wrought iron.................

77

26

Cast iron..................

44

15

Dantzic oak................

4.5

1.7

Red deal..................

3.3

1.2

To find the Strength of Round Columns exceeding 25 Diameters in Length. (Mr. Hodgkinson's Rule.)

(Diameter, ins.)3.6 / (Length, ft.)1.7 X Tabular No. = Breaking weight, tons.

A column should not be loaded with more than 1/3 of the breaking weight in any case, and as a general rule, not with more than ¼ ; for purposes of machinery, not with more than 1/6 to 1/10 according to circumstances.