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318 Molesworth’s pocket-book
Telegraph Construction, by R. S. Brough—
continued.
Material.
....
Wrought Iron (Clark)1.
Solid bars, and circular welded tubes ..
Circular riveted tubes of plate iron, with )
transverse joints double riveted .. .. 5
Plate beams............ .. .. .. .,
Cast Ibon (Clark).
Solid bars .. ., .. ...............
Tubes .................................................
Wood (Rankine).
Fir: Red Pine .......................
„ Spruce.......................",
„ Larch................................ . '
Saul ............................ \
Teak ................................
Values off
in tons per
square inch.
18 to 20
13
18
13
11
3 to
4 „
2 „
1
6 „
4
5
4
10
9
Posts of uniform strength may be designed by
means of the following formula), x being the depth
of the post in the direction of the strain at the
ground line, and d its depth at the top:
For solid
posts.
P . h = k . i . &x-3,
X 7
X .
= 2 if be kept constant,
3
d — - x if b vary with x.