CRANE. 
on eitlier wheel, may be brought forward 
toVoik in either a, b, or c, at pleasure. 
Now D being one foot in diameter, and a 
being two feet, the latter will revolve once, 
while the former revolves twice ; this power 
is suited to light weights. When the resis- 
tance is greater, the power must be increas- 
ed by removing D farther from the centre of 
the windlass e, and applying it to the second 
wheel h, which being three times the dia- 
meter of D, will turn only once while the 
latter makes three, revolutions : again, when 
the weight is vei-y great, D must be made 
to work upon the largest wheel c, which 
being four times its diameter, will cause D 
to tarn four times while c turns but once. 
The figure is not exactly in the above pro- 
portions ; but the explanation will suffice to 
render that mimitia of less importance. D 
is turned by a crank-handle, or winch, and 
is made to fit into three difterent sockets, 
where its axis is keyed down opposite to 
whichever wheel is to be acted upon. It 
should have a small ratchet, or pall, to pre- 
vent its retrocession, in ease the weight 
should overpower the operator. 
Some cranes are made to weigh goods as 
they are raised; but this can seldom be 
done with accuracy, though the general 
estimate may be correct enough for ordi- 
nary occasions. It is done by allowing the 
jib, or projection m, (fig. 2) to play on a 
joint at n, and by having a moveable weight 
at the other end of the beam, s, of which 
the jib forms a part, with an index, on the 
principle of the steel-yard. But this cannot 
answer where very heavy articles, such as 
cannon, &c. are to be raised, as the joints 
■would soon give way. Whatever may be 
the construction of cranes, power and safety 
ought to be the principal objects. 
We shall proceed to describe some other 
cranes that are much in use in the present 
day. Fig. 1, Plate Cranes, is an elevation 
of a crane sideways, and fig. 2 is a plan ; 
AB is a stout beam, turning in a cast iron 
collar at B, affixed to beams in the floor of 
the wharf; it goes down about twelve feet 
below this, and has a steel pivot in the 
lower end, which works in a brass collar, so 
that tlie beam A B can turn round freely 
w'ithout shake ; C D are the two beams of 
the jib, with a pully at E, over which the 
chain for hoisting the goods works; the 
other end of this chain is wound round a 
roll, e, 1 foot diameter ; a cog wheel, mark- 
ed too, of too teeth, turned by a pinion of 
7 leaves on the same axle with another 
wheel, 31, of 31 teeth ; this is turned by a 
pinion, 14, of 14 teeth. If great power is 
required, the winch handle is applied to a 
square on the end of the spindle of the last 
pinion, and for less weight the winch is put 
on the axle of 31 : when this is the case, the 
pinion 14 must be disengaged from its 
wheel, by sliding its axle lengthways. G 
is a clip to keep the pinion in or out of 
gear, as it has been placed by the attendant. 
A plan of it is also shewn in fig. 2 : the two 
semicircular bands in it fit into grooves 
turned in the spindles, and the weight a at 
the end keeps them in : this prevents them 
moving endways: when the w'eight a is 
raised it releases them both ; and when they 
are moved the clip fits into another groove 
turned in them, so as to prevent their re- 
turn. The frame containing the wheels is 
formed by two cast-iron crosses, bolted to 
the main beam A B by the ends of their 
verticle arms, the two other arms forming 
the bearing for the wheels. 
Cranes of this kind are now coming into 
very general use in London, as they require 
110 expensive framing over them, and they 
can be turned all round. A further advan- 
tage they possess, in common with several 
other kinds, is the chain not being bent sud- 
denly round the small pulleys over the jib 
when they are swinging overland, as in the 
common kind, and fig. 4. 
A crane of this kind, which we saw at 
Woolwicli Warren, had an apparatus (shewn 
in fig. 3) attached to it for lowering with 
safety great weights without any exertion 
of the workmen. It consists of a cylinder, 
bde, of cast iron, smoothly bored through • 
fg is a passage connecting the top and bot- 
tom of the cylinder, and h a cock by which 
this passage can be closed: i is a piston 
fitting the cylinder, and k the rod affixed 
to it, moving through a stuffing box in the 
lid of the cylinder : the axis of the wheel 31 
(fig. 1 and 2), or one in the place of it, has 
a crank on it working the piston rod of the 
cylinder (fig. 3), which is bolted fast to the 
back of the beam A B, with the usage 
sliding motion to render its motion parallel. 
The cylinder is filled fidl of oil, and as the 
handle of the crane is turned the piston is 
moved up and down in the cylinder : now, 
if the cock h is open the oil flows freely 
from one part of the cylinder to the other, 
without obstructing the motion of the crane ; 
but if it is closed, the oil finding no other 
passage, and being an incompressible fluid, 
stops the piston and the descent of the 
goods suspended by the crane. By open- 
ing the cock partially the friction (or, as it 
