642 REPORT—1883. 
of the western jetty. At Morecambe Bay force-pumps were used, worked by a 
2-horse steam-engine; here, at Southport, advantage was taken of the pressure on 
the town mains. At Morecambe the cost of sinking was 2s. 6d. per foot, and at 
Southport only 43d.; an economy due to the use of the town water. At Southport 
twelve piles were repeatedly put down in a tide; at Morecambe the average was 
scarcely two in a tide. 
For hard gravel, shale, or soft rock, such as is met with in the Mersey, I adopted 
a corkscrew form. Abroad, notably in Brazil, where the deposits are mostly allu- 
vial, the ordinary bladed screw pile was used in one case for a bridge of ten spans, 
in 35 to 40 feet of water, with perfect success. In the Solway Viaduct, more than a 
mile long, it was originally intended to use the screw pile; but after getting through 
a depth of about 4 feet of sand, it was found that there was such an exceedingly 
hard stratum of gravel, bound with stiff clay underneath, that the screws would 
not enter, and a round pointed pile was substituted. I have used metal piles 
instead of cylinders, on account of the greater ease and economy with which they 
are put in place. In the case of the Eau Brink Viaduct, near Lynn, the span was 
111 feet, the screw of the pile 3 feet 3 inches diameter, and the pile 18 inches in 
diameter. Five piles were placed under each girder, and as the metal in these was 
equal to a cylinder 4 feet 4 inches diameter, three times the bearing surface 
was obtained with the same weight of metal. The process of screwing is much 
simpler than that of sinking cylinders by the pneumatic process, and the whole 
operation is handier and more economical, wherever it can he adopted. 
A great revolution in driving timber piles was effected by Mr. Nasmyth, who 
adopted the principle of his steam hammer to the purpose. The Nasmyth pile- 
driver was first employed at an extension of the Devonport Docks, where a very 
large number of piles had to be used. At the first trial it did in four and a half 
minutes the work which by manual labour could only be done in twelve hours, and 
was perfectly successful from the first moment of trial. The Nasmyth pile-drivers 
generally in use weigh about 24 tons; the boiler weighs 76 cwt.; the hammer 
weighs about 30 ewt., and delivers a blow every second on the head and shoulders 
of the pile, driving it down in ordinary soil from 5 to 10 feet per minute. A 
small engine moves the machine on a tramway, and three men manage the whole 
apparatus. 
Tron cylinders for foundations were first used by Mr. Redman, on the Thames, 
at Gravesend, for the construction of the Terrace Pier in 1842, and they have since 
been largely employed all over the world. Many improvements have been made 
in the methods of sinking cylinders since their first introduction, when they were 
sunk into the yielding soil by pressure from above. The first practical application 
of compressed air to the sinking of cylinders appears to have been made in 1839, 
at Chalons, where it occurred to the engineer to cover over the top of the cylinder, 
and by the pressure of the air to drive out the water, and admit the workmen 
inside to remove the earth, and gradually to allow the cylinder to sink into its place. 
Lord Dundonald had previously patented the same system in this country, where it 
was first applied in constructing Rochester Bridge. 
Several mechanical contrivances, more or less perfect in their operation, have 
been used for removing the soil inside the cylinders, to assist in lowering them into 
place. Mr, Milroy, Mr. Bradford Leslie, and others, have designed and used. these 
mechanical aids with much success on the Portpatrick railway bridge across Loch 
Ken, at the Gorai bridge in India, and on the Caledonian Railway viaduct over 
the Clyde, and elsewhere. By their means considerable speed has been attained 
in sinking cylinders in difficult circumstances, and where the employment of 
the atmospheric system would probably have been impracticable or unusually 
expensive. 
Sir William Fairbairn attributes the suggestion of caissons to General Sir 
Samuel Betham, in 1798; and the ordinary floating caisson, to which the sugges- 
tion applied, has been very extensively used. In the construction of the Keyham 
Docks, Sir William applied a new form of caisson, to obviate difficulties created by 
the great width of the dock entrance and the depth of the basin, and to save the 
time lost in pumping out the old form of caisson, The new caisson was designed 
