3. Required the side of a square bar to support the sameweight.

ooft

Here —-= 13‘4 and N /13 - 4=3 , 7 side of square.

14-75 1

4. What ought to be the circumference of a rope to lift aweight of 7 tons, or 140 cwt.

Here =50-9 and N /50-9=7-l inches circumference.2-75

On the Transverse Strain.

It is not necessary here to enter into the physicaltheory of the resistance of timber and other materialsto a transverse strain. It will be sufficient to state,that, according both to theory and practice, it is foundthat the transverse strength of timber, iron, and allother rigid bodies of rectangular section, varies di-rectly as the breadth multiplied by the square of thedepth, and inversely as the length; and consequently,the breaking weight being ascertained experimentallyfor any given dimensions, for any given material, andaccording to any mode of fixing, it may be found forany other dimensions, the material and mode of fixingbeing the same. But the resisting power dependsmuch upon the method of fixing or supporting thebeam, and also on the distribution or place of the load.All the more general cases are stated below.

1. A beam may be fixed at one end and loaded at the

other.

2. It may be fixed as above, but uniformly loaded.

3. It may be supported at both ends and loaded in the

middle.

-1-. It may be supported the same, and the load appliedat a point, not the middle.