36

One foot long,inch square.

Weight in ounces.

One-fourth * the weight inounces, which would drawasunder the material in thefirst column in direct tension.

Wrought Iron

7788 _

54.083

56000 X 16_

224000

144 —

4 “

Hempen Rope

1236

8.587

5264 X 16 _

21056

144 —

4 ~

Oak

845 _

5.868

10000 X 16 _

40000

144 ""

4 —

Fir

600 _

4.166

12000 X 16 _

48000

144 —

4 ~

Ash

600 _144 —

4.166

17000 X 16 __

1 4 ~

68000

The weight in suspension to be takenas follows: —

Ounces.

The road-way on the bearers tobe 4 inches thick of some mat-ter, weighing, per foot cube,

600 ounces - 200

Weight of the wind in hurricanes,per foot superficial, (49.2 x 16) 787

* Mr. Emerson thinks one-fourth the breaking strengthshould be taken as the practical strength. See his Me-chanics. Mr. Rennie, page 27, 3d Report, MenaiBridge, 29th April, 1819, says, “ I have before statedthat I consider a bridge such as this is, should be abovefour times as strong as a mere theoretical calculationgives it.”