434 molesworth’s pocket-book
Power required to Punch Boiler-plates, &c.
P = Power required in tons.
T = Thickness of iron in inches.
D = Diameter of hole in inches.
U = 80 D T.
Punching copper requires a force of about |
that required for iron.
Dynamometer.
To estimate the horse-power as indicated by
the dynamometer :—
L = Length of lever in feet.
N = Number of revolutions of shaft per minute.
W = Weight applied to the end of the lever in
lbs,, including the weight of the scale.
Actual horse-power = • 0001904 WLN,
Dkedgins Machines.
Depth of Number of Length of Nominal
Water Buckets. Bucket Ladder. Horse-power.
Pppt ’ Feet.
18 ’ 31. .60 20
20 36 63 25
25 45 78 30
C = No. of cube feet excavated per minute.
H =± Height to -which the earth is to be raised.
P = Actual horse-power required.
P = C (-004 H + *35) for stiff clay and gravel.
= C (-004 H + ’15) for soft clay and mud.;
Depkeciation of~Machinery, &c„ per Anncm on First Cost.
Deprecia- tion. Wear and Tear. Total.
Engines .. .. .. Boilers .. .. .. Machines .. .. .. Mill work and gearing Bands and belts .. 3 per cent. 1 „ 5 „ 3 „ 3 per cent. 4 „ 5 H 2i „ 45 „ 6 per cent. 10 „ 8 „ 51 „ 45 „