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G gonaE.— Description of Patent Slip at Wellington. 17 
of the vessel to be raised. Small blocks or pulleys are fixed in positions to 
guide the ropes in the proper directions, both for the sliding blocks and 
the palls. 
The steam engines for working the slip consist of two 25 horse- 
power horizontal high-pressure engines, manufactured by Messrs Appleby 
Brothers, of London. Steam is supplied to the engines by two single-flued 
circular boilers, 30 ft. in length and 5 ft. in diameter. They are erected in a 
building about 50 ft. distant from the engine house. The reason for placing 
them so far distant was to avoid the expense of a heavy cutting that would 
have been required to place them close to the engines. It is not found that 
any loss is sustained beyond the expenditure of steam necessary to warm the 
steam-pipe in the first instance, the steam-pipe being, of course, covered in with 
.hair-felt. The boilers are supplied with water by means of a Giffard's patent 
injeetor, but ean also be supplied by the pumps attached to the engines; 
the usual pressure gauges, safety-valves, blow-off cocks, etc., being also fixed. 
The boilers were constructed at Messrs. Kennard Brothers’ works at Crumlin, 
being sent out to the colony in sheets, and rivetted together on the work. They 
were tested, by hydraulic pressure, to upwards of 100dbs. to the square inch 
before being set into their places in brickwork ; the usual pressure at which 
they are worked when a vessel is being raised is 45 105, to 50105. to the 
square inch. 
The engines are attached to a train of wheels, or winch, which, when 
working in slow purchase, multiply the power of the engines seventeen times, 
while a quicker purchase multiplies the power of the engines nine times. There 
are seven cog-wheels in the winch, the last and largest being fixed on a shaft 
of 14in. diameter, on which the chain wheels work ; the wheel for the large 
chain being 7 ft. in diameter, and for the small chain 9 ft. "These wheels are 
loose on the shaft, and are put in gear by means of a clutch worked with a 
screw and haud-wheel The chain wheels are grooved to take the chain, 
having suitable teeth cast in the groove for each alternate link of the chain to 
bear upon. The hauling-up chain is 1,700 ft. in length, and made of iron 
Jin. in diameter, each stud link being 18in. in length. For small vessels of 
500 tons or under, this chain is worked single, being shackled round the 
pulley wheel at the head of the cradle; but when it is required to raise a large 
vessel the chain is worked double, the return end being secured to an anchor 
block fixed in a suitable position near the winding engine. The small chain, 
or lowering-out chain, is of 1} in. iron, one-half being made in long links to 
suit the teeth of the wheel, and the remainder in lengths of ordinary short-link 
chain shackled together. This chain is secured in the form of an endless 
chain, both ends being shackled to the head of the carriage. A pulley wheel 
‘is fixed at about 165ft. from the outer end of the ways, round which the 
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