118
Molesworth’s pocket-book
Nasmyth’s Steam Pile Deivek.
Weight, 72 cwt.; diameter of cylinder, 16 inches; fall,
3 feet-; making 60 blows per minute. It was found that it
required 15 blows to drive a pile 1 foot, which was equivalent,
ill soil of the same character, to 15 blows of an ordinary pile
driver with a ram of 15 cwt. falling 16 feet; the ordinary pile
driver, however, only made 1 blow in 4 minutes, or of
the speed of the steam pile driver.
Sheet Piling.
Birds-mouth bevelling 120°
Angle of shoeing . • 25°, with horizon.
Ringing Engines.
W = I'rom 4 to 8 cwt.
Power to each ringing engine
= 1 man to each 40 lbs. weight of ram.
Foundations.
(Rankine.)
W — Weight of soft ground per unit of volume.
d — Depth of foundation.
a = Angle of friction.
P = Pressure on base per [unit of area which will
support building
Blows versus Pressu(In shaping or dividing
substances).
(Kick, • Tran§. Inst. Civ. Eng.,’ vol. xliv.)
1. More waste of labour is caused by blows than by constant
steady pressure.
2. One blow, exercising the same mechanical power as that
of a known steady pressure, will not produce an equal effect.
3. The mechanical power necessary to effect temporary
alteration of a substance up to its limit of elasticity, if applied
through the medium of blows, will not affect that substance
up to the limit of elasticity.