Chap. XXI.
1279
Pumps for the supply of water to the boiler arc usually two in number, placed beneaththe piston-rod of the cylinders ; they suck a portion from the tender, and then force it intothe boiler : these pumps have spherical valves, made ot metal, which rise within a cylinderha\ ing four apertures for the passage of the water.
To fill the boiler a square pit should be sunk, large enough to admit a pair of 3 feetwheels, fixed on an axle similar to the carriage wheels; they should have no flanges, andtheir circumference should come up through the rails, and be made to lock at pleasure.When it is required to pump water into the boiler, the engine must be brought with itsdriving wheels directly over those in the pit, and these latter being unlocked, the steamis let gradually on, and the pumps worked as long as is necessary for filling the boiler,without the engine advancing from where it was placed.
The Steam JITiistle is fixed to the boiler; by turning the handle, the cock placed inthe pipe is moved round; the steam issues with suchviolence that when it enters the brass hemispherical cupat the top, it strikes in its passage the thin edges of ahorizontal brass plate, producing a shrill and loud whistleas it escapes.
We shall now give the dimensions of some of the mostapproved locomotives : those used upon the Liverpool andManchester line have cylinders 10 inches in diameter, anda length of stroke of 16 inches; their boilers are 3 feet indiameter, and 6 feet in length, within which are inserted90 tubes, 2 inches in diameter : the fire-box is 24 inchesin length, and 36 in width, with a similar height, 'J7iearea exposed to radiant caloric is 25 feet 6 inches super-ficial, whilst the area of the fire-grate is 6 feet: thesuperficial area of the tubes in contact with the heatedair is 283 feet.
In an engine where the diameter of the cylinder is 11incites, and the length of stroke 16 inches, the boiler is 3feet in diameter, 6} feet in length, and contains 132 tubes,lg inches in diameter; the length of the fire-box is 22inches, the width 40 inches, and the height 34 inches.
The area exposed to the radiant heat is 32] feet; thatof the fire-grate nearly 7 feet, and the area of the tubesexposed to the contact of the heated air is 379 feet.
An engine with 12-inch cylinders, and with the samelength of stroke, has a boiler 3 feet in diameter, and 7feet 9 inches in length, with 104 tubes, 1 in diameter :the fire-box is 24} inches in length, 43 inches in width,and 37 inches in height above the fire-bars. The areaexposed to the radiant heat is 39] square feet; that of thefire-grate is 7} feet, and the total area of the tubes 354feet.
An engine of 14-inch cylinders on the Leicester Rail-way, and 18-inch stroke, has a boiler 42 inches in dia-meter, 90.} inches in length; 97 tubes 2} inches in diameter ; the length of the fire-boxis 26 inches, the width 41, and the height 44 inches: the area exposed is 46 superficialfeet, and that of the fire-grate nearly 7} feet. The area of the tubes in this engine is420} feet: the total weight, when in working trim, 10 tons 8} cwt. ; the dimensions ofthe steam way to the cylinder are in length 7 inches, and width 1} inches.
An engine on the Newcastle and Carlisle line, with 15-inch cylinders, and a length ofstroke of 16 inches, has its boiler 45 inches in diameter, 8 feet 6 inches in length, and 145tubes, 1| inches in diameter. The fire-box nearly 39 inches in length, 41} in width, and44} inches in height: the area exposed to radiant heat 60 feet 4 inches, and that of thefire-grate 11} feet superficial. The area of the tubes in contact with the heated air nearly547 feet.
An engine on the Great Western, with 16-inch cylinders, and a stroke of 16 inches,
has its boiler 4 feet in diameter, and 8 feet 6 inches in length ; the number of tubes 167,
all 1| inches in diameter. The fire-box in length 41] inches, in width 47, and in heightabove the bars of the grate 45] inches. The area exposed to radiant heat 70 superficial
feet, and the area of the fire-grate 136 feet. The area of the tubes exposed to the heated
air was 54] square feet.
The above engines were constructed by R. Stevenson and Co., at Newcastle-upon-Tyne ;the following were made by Messrs. R. & W. Hawthorn of the same place. An enginewith 12-inch cylinders, and a length of stroke of 16 inches, had the diameter of the boiler
Fig. 2053.
STEAM WHISTLE.