ON THE APPLICATION OP WATER-PRESSURE MACHINERY. 419 
hauling of trucks and traversing machines are all performed, or about to be 
*o, by means of hydraulic pressure supplied by one central steam-engine with 
connected accumulators. Mr. Rendel also, after having successfully adopted 
the low-pressure system to the working of the gates and shuttles at Grimsby, 
has since applied the high-pressure, or accumulator system, to the same pur¬ 
poses at other new docks, and a similar adaptation is being made by other 
eminent engineers at most of the new docks now in course of construction. 
I have also adapted hydraulic machinery to the opening and closing of 
•wing-bridges and draw-bridges of large dimensions; and, in fact, there is 
waroi lv any mechanical operation to which human labour has been hitherto 
applied as a mere moving power, which may not be efficiently performed by 
means of water-pressure emanating from a steam-engine and accumulator. 
bv(!ti if hand-labour be retained as the source of the power, the intervention 
of an accumulator will in many cases both economise labour and increase 
despatch. For example, a pair of heavy dock-gates requires the constant 
attendance of a considerable number of men whose labour is only called into 
action occasionally, viz. when the gates are being opened or closed. Now, 
1 a ^ cumu Iator, charged by hand-pumps, were used, the labour employed 
I J0 constant., instead of occasional, and the power collected in the ac¬ 
cumulator by the continuous process of pumping would be given out in a 
concentrated form, and thus the ultimate result would be effected with fewer 
,a, i' aaa grater despatch than where manual labour is directly applied. 
I , . m °f pumping-engine which I generally use for charging the accu- 
i. J 18 represented in Plate 11. fig. ‘2. It consists of a horizontal steam- 
Foi- 1 . 1 ! Cr * W ' t l * wo force-pumps connected directly with the piston. These 
co-pumps are supplied with water from a cistern over the engine-room, into 
etur • water discharged by the cranes is generally brought back by a 
u-pipe, so that the water is not wasted, but remains continuously in use. 
friction ,a ?[ essi l ro representing a column of 1500 feet, the loss of head by 
t 0 l 110 t,lc P'Pes forms so small a deduction from the entire column as 
tb 0 “ ,atter of no consideration, and consequently the distance at which 
, llav l° , ma y. b(i situated from the points where the hydraulic machines 
li j s j s °i little importance, except as regards the cost of the pipe, 
each cxiri f' however, >f the pipe be very long, to apply an accumulator at 
With rJ 01 a’ 80 as c ^ ar g e the pipe from both ends. 
1 f ‘^t adrfj l ° the meoha ‘'ism of hydraulic cranes, the arrangement which 
hjdraulin 6d ’ ant *. * iave ever erince adhered to, consists of one or more 
ami pull(n!l rt f S ? 8, i' V ' t * 1 a set °f leaves, used in the inverted order of blocks 
front a cunm ° P ,.- , Purpose of obtaining an extended motion in the chain 
c, «u*cter2 , ey s,lort 8lrolce of the piston. This construction, which 
*hich 1 have nea .. y®!! the varieties of the hoisting and hauling machines to 
presents on r hydraulic pressure, is exhibited in Plate III. fig-3, which 
'"''rfold. i n e these presses with sheaves attached, to multiply the motion 
herably [ Cils .? s " here the resistance to be overcome varies very consi¬ 
der Sep,,,-!, i ra y ena P% three such cylinders, with rams or pistons acting 
c °rtlin<j to tu* y or COn j°iotly upon the same set of multiplying sheaves, ac- 
, In hydJauil a “ OUDt ° f PO"er required. 
a ho for , vill£ , in Cr --the power is applied, not only for lifting the load, but 
° r chain oneraK^ * le jib, which latter object is effected by means ol a rack 
° ec ted either »'?? ° U ^! e i’ as o °f the moveable part of the crane, and con- 
a ®team. t . n g| 1 1 a Cylinder and piston having alternate motion, like that of 
.jrnate action ^ W,t ^ two prewea applied to produce the same effect by 
DCe an y sensible elasticity in water renders the motions 
2 e 2 
