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what novel in construction, the strut of the jib being in two 
parts, forming an angle with each other, whereby great 
headway is allowed for the piling up of goods. These cranes 
are worked with ease by one boy, who performs all their 
evolutions with the greatest rapidity and certainty, by two 
handles governing the valves of the hoisting and turning 
cylinders. The machinery is generally concealed under the 
pavement of the wharves, or in some other convenient locality. 
When it is probable that the loads to be raised by the hydro- 
static crane will vary greatly in weight, three or more 
hoisting-barrels are applied, the rams of which can be made 
to act in groups either of a single one, or more than one, so 
as to effect a saving of water when a light load is to be 
raised. 
The system of hydrostatic machinery at Great Grimsby 
Docks consists of three classes of cranes ; one class for the 
purpose of loading or unloading ships, another for loading 
and unloading waggons, and a third class is for the service of 
the warehouses ; they vary in power from one to three tons. 
In addition to these cranes, there is an apparatus on a large 
scale for working the gates of the locks, and also for convey- 
ing persons to the top of the accumulator tower. The doors 
of the sluices by which the locks are filled and emptied, and 
the mud scoured away from the landing-places and dock- 
entrances, are also raised and lowered by hydrostatic pressure, 
which is further applied to facilitate the weighing of goods in 
the trans-ship sheds, by preventing the swing of the scales, and 
rendering the placing of the goods in them more easy. The 
machinery by which the dock gates — twelve in number, six of 
them spanning a distance of 70 feet — are manoeuvred, is 
arranged as follows : — In the proper positions, and concealed 
under the pavement of the wharves, are fixed three large 
hydrostatic cylinders, furnished with pistons, and piston-rods 
passing completely through them. The piston-rod of each 
