THE MERSEY TUNNEL. 377 
main beam to point of balance-beam. This rod is composed of oak, with 
malleable iron straps, and firmly bolted along its whole length ; it is fitted 
with brass bushes, gibs, and cotters at each end. At each side of this rod 
there is a malleable iron rod, extending from main beam to a cast-iron 
crosshead. This crosshead is placed below the point of balance-beam, and 
to it the pump-rods are attached. This arrangement brings the pump- 
rods direct on to the main beam, on which there is but 13 inch of lateral 
motion, thus avoiding the large swing at the point of balance-beam, and 
keeping the rods travelling upwards and downwards almost in a direct 
line, a matter of great importance in pumping machinery like the present, 
having a stroke of 15 feet. The pump-rods are made of wood, having 
four malleable iron plates at each joint. The rods are bolted to malleable 
iron forks, having tapered ends turned and fitted—one to the cast-iron 
crosshead at top end, and one to the plunger at bottom end, both held in 
position by a collar. The plunger pump is of the ordinary kind, having 
a stroke of 15 feet. The plunger is 40 inches in diameter, and turned 
true throughout its entire length, fitted with two malleable iron hoops 
at top end. The suction and delivery valves are of brass, mounted with 
strong steel lids having leather faces, also malleable iron guards, and 
fishing tackle. The rising main is of sufficient size to allow both valves 
to be drawn up from the surface, thereby avoiding much trouble and 
inconvenience during repairs; the working barrel is bored its entire 
length slightly larger than the plunger; the clack seats are provided with 
openings, 4 feet 6 inches and 3 feet 9 inches, to allow of easy access to 
the valves ; the doors for these openings are of steel. The whole pump is 
set on two massive cast-iron girders, the suction-pipe passing up between 
them ; these girders at each end rest on oak, which is bedded to a cast- 
iron sole-plate, resting on concrete set in strong cast-iron boxes, which 
are continually in the water. The weight of engine and pumps is 262 tons. 
The boilers, eleven in number, have been manufactured by Messrs. Daniel 
Adamson and Co. They are of the Lancashire type, being 28 feet long 
and 7 feet 6 inches diameter, each boiler having two flues 3 feet diameter, 
and each flue crossed by five conical circulating pipes. They are built 
for a daily working pressure of 70 lbs. per square inch, and are steel 
shell boilers, having all the rivet-holes drilled after the plates are bent 
into position—that is, into the form they take in the boilers—thus 
ensuring a perfectly true and parallel hole for the rivet. The edges of the 
plates are planed; the flues are solid welded in tbe longitudinal seams; 
the conical circulating pipes are solid welded into the flue-rings, and the 
circular joints of flue-rings made with Adamson’s anticollapsive flange- 
seam. Thus no rivets or edges of plates are exposed to the action of the 
flame. The edges of the flange-seam are turned up by machinery. The 
boilers are riveted up throughout by special riveting machines. The 
shells are double-riveted in the longitudinal seams, and cross-jointed, the 
circular seams of shells being double-riveted. The back ends of the 
boilers are flanged and riveted to the shells, and the front ends are riveted 
to outside angle steel rings. The boilers are properly and strongly stayed 
with gusset as well as longitudinal bolt-stays, and fitted with round and 
oval manholes, and full complement of mountings and fittings to each 
boiler, the safety-valves to each boiler being two—viz., dead-weight valve 
and high-steam and low-water valves. Messrs. Adamson and Co. have 
made over two thousand steel boilers, and have them working, dating 
from twenty years old, with the most satisfactory results. This success 
