Information on the weight, measurement, and strength of timber is scattered through various books, from which the following table is extracted: -

Timber, Selected Quality.

Weight lb. per cub. ft.

Ultimate Tensile

Strength tons per sq. in.

Ultimate Compression tons per sq. in.

Coefficient of Transverse Strength.

Ultimate Bearingl.

Pressure tons per sq.

in. across Grain.

White pine ......

28

_

1.8

3.8

•27

Spruce fir.........

31

1.5

25

3.6

•22

Larch .........

35

1.5

2.5

3.5

-

Honduras mahogany

35

15

2.8

4.9

•58

Elm............

37

2.0

3.0

3.0

-

American reel pine ...

37

-

2.2

4.0

-

Northern pine......

37

15

2.9

4.0

•60

Kauri pine ......

38

-

2.8

4.8

-

Ash............

45

2.0

35

5.0

-

Beech .........

47

19

3.8

4.5

-

Baltic oak ......

48

3.0

3.2

4.3

-

Pitch pine ......

50

-

2.9

5.0

•76

English oak ......

50

3.0

3.2

50

•90

Teak .........

50

30

3.8

5.0

-

Spanish mahogany ...

53

1.8

3.0

5.0

1.9

Green heart ......

60

-

5.8

8.0

-

(1)

(2)

(3)

(4)

(5)

(6)

The safe load in tension and compression, columns 3 and 4, would be from one-tenth to one-fifteenth of the amounts given. The safe bearing pressure across the grain of timber as at the ends of a beam will be about one-fifth of the amounts given in column 6. Column 5 gives the coefficient C in the formula W = C b d2 / L, and the safe load would be about one-sixth of W for temporary work, or one-tenth for permanent loads.