154 ON THE ENGINEERING MANUFACTURES 



supply has remained limited, owing to such supply being confined to 

 districts generally unfavourable for the erection of works, and the im- 

 portant and extended application of hydraulic machinery, which has 

 taken place in nearly all the principal docks, railways, and government 

 establishments in this country, is due to the invention of the " accumu- 

 lator" for producing artificial pressure, usually made equal in effect to a 

 head of water of about 1,500 feet. 



This high pressure system has been adopted, with economy to a 

 great variety of purposes, such as to cranage, waggon lifts, coal drops, 

 hoists, and tipping machines, to the working of turn-tables, traversing 

 machines, hauling machines, capstans, &c, but in no one branch of 

 labour, perhaps, has this economy been more exemplified than in the 

 loading and discharging of vessels, particularly those employed in the 

 coal trade. 



Nearly 1,800 hydraulic cranes, hoists, and other machines of this 

 description, have been applied, and 174 steam engines, having a collec 

 tive power of more than 5,200 horse power, are employed in supplying 

 the pressure required for working them. In addition to these, 177 hy- 

 draulic engines of various forms and powers have been produced, and 

 23 moveable bridges receive their motive power from hydraulic 

 machines. 



The most novel and noticeable arrangement for the discharge of coal 

 from vessels, through the intervention of hydraulic machinery, is to be 

 seen on board a vessel, belonging to Mr. Cory, moored in the River 

 Thames. This vessel, originally built for other purposes, has been con- 

 verted into a floating wharf, and is fitted up with a steam pumping en- 

 gine, accumulator, six hydraulic cranes (which weigh the coal at the 

 same time), two hydraulic capstans and a variety of appurtenances for 

 facilitating the work by day and by night. 



Rapidity of discharge is the great feature of this scheme. Steam 

 colliers carrying 1,200 tons of coal are delivered in ten hours. Such 

 vessels plying between the Tyne and the Thames, have accomplished 

 the voyage in 96 hours, i. e. they have loaded and discharged each cargo 

 in one tide, or made the passage in three tides each way. Two such 

 vessels can be delivered at the same time alongside Mr. Cory's floating 

 wharf, thus rendering the power equal to the discharge of about 5,000 

 tons of coal, in the 24 hours. 



The application of hydraulic hoists for shipping coal, has met the 

 difficulty formerly felt in loading from low levels, at a comparatively 

 moderate cost, which may be seen from the following figures : — 



At the Newport Docks, Monmouthshire, in the year 1862, 218,486 

 tons of coal were shipped from three hydraulic hoists, worked by six 

 men. The sum paid in wages, stores, and repairs, amounted to 501Z. 6s. 2d. 

 The cost of supplying the pressure amounted to about 2501., which 

 gives a charge of about 0-276 of a penny per ton for the pressure, and 

 - 552 of a penny per ton for wages, stores and repairs. These figures 



