OF THE WATER SUPPLY.

390. The number of engines leaving the terminus of a road determines the amount of water necessary at the principal stations; and the character of the road and of the traffic fixes the location and size of the way water stations. The amount of traffic being pretty equally distributed over the length of the road, the tanks should be placed at equal equated distances; thus the engines will need to water at closer points upon steep grades than upon level roads. Generally, however, the water is taken where it can be got, the location of streams and springs fixing the place. Steam, hydraulic, wind, human, or animal power may be employed to raise the water to the tank. Oftentimes high springs will fill the tanks without the application of artificial power. As we find the liquid water in nature it is more or less impregnated with vegetable, gaseous, and saline matter, which often impairs its fitness for mechanical purposes. These admixtures are derived from the rocks and ground over or through which the water flows. The incrustations which form in boilers are caused by the precipitation of the impurities in consequence of the concentration of water in the boiler. They may be effectually removed, no matter what their nature, by boiling charcoal in the water. If the water, previous to filtration, can be heated, to expel all the air and carbonic acid gas, which is often the solvent of the foreign matter, the filtering process will be accelerated, and will be more effectual. Rain water is more pure than any other; practically, perfectly so. River water comes next to it. Spring water is generally adulterated with basic salts in various forms, most of which may be precipitated by gently heating and filtering through charcoal.

391. Fig. 157 shows a convenient form for a tank house, with pump and heater.

Fig. 157.

A shows half interior section of the tank.

B, half elevation of tank.

C, pump; C′, supply pipe; d, suction pipe and strainer.

E, heater.

e, the short, and h, the long pipe.

H, the discharge pipe.

G, discharge valve.

I, counter weight for discharge pipe.

K, wheel for weight rope.

L, scale showing amount of water in the tank.

The heater shown in the cut is made of a coil of two inch pipe of iron. The short pipe descends from within six inches of the bottom of the tank to within two or three feet of the floor; then bending four or five times around spirally, turns up through the centre of the coil, and runs three or four feet into the tank. A small grate is placed in the lower part of the coil, and the whole apparatus is cased in sheet iron. By such an arrangement of pipe, circulation is obtained, and the water in the tank is kept quite warm. The following rules and tables may be found convenient.

392. The velocity of water in any pipe necessary to discharge a given quantity, in a fixed time, is expressed by

144C
a.

Where C is the number of cubic feet per hour, and a the area of the pipe.

393. The head necessary to send water through a given length of pipe, of any diameter, is shown by the formula

C
D + C′ = H.

Where C = a constant.

C′ = constant for diameter of pipe.

D = diameter of pipe.

H = heads required.

The experimental values of C and C′ are as follows: Let V equal the velocity in feet per minute, and we have

V.	C.
60	8.62
70	11.40
80	14.58
90	17.95
100	21.56
120	29.70
140	38.90
150	44.00
180	62.13

Also, the values of C′ are

Diameter of pipe.	C′.
2	.000
3	.006
4	.028
5	.053
6	.078
7	.104
8	.134

EXAMPLE OF USE OF PRECEDING RULES.

Required the head of water necessary to send 1,333 cubic feet of water, or 10,000 gallons per hour, through an eight inch pipe one thousand feet long.

The velocity by rule one will be

1333 × 144
8² × .7854 = 3818 feet per hour, or 64 feet per minute.

By rule two (the value of C for 60 being 8.62, and for 70 11.40, that for 64 is 10 nearly), we have

10
8 + 0.134 = 1.23,

which multiplied by ten (the number of times that one hundred is contained in one thousand feet, the distance), gives the result, twelve inches or one foot, which is the required head; and if the entrance to the tank is twenty feet high, we have, as the necessary head, 20 + 1 = 21 feet.

394. The formula expressing the power of an engine to raise a given amount of water is

WV
33000.

Where W is the weight of a column of water, and V the velocity in feet per minute; also 33,000 the expression of a horse-power. For example, how many horse-power must an engine possess to raise one thousand cubic feet of water per hour through a six inch pipe fifty feet high?

The velocity will be

1000 × 144
6² × 0.7854 = 5093 feet per hour,

or eighty-five feet per minute. The weight of a column of water fifty feet high and six inches in diameter is

6² × 0.7854 × 50 × 12
1728 × 62½ = 613.6 lbs.

Also,

612½ × 83
33000 = 1½ horse-power nearly.

395. Among the pumps now in use for raising water at railroad stations are Carpenter’s rotary, Worthington’s, McGowan’s, and that of Messrs. Perkins and Bishop, either of which answers every purpose.

396. TABLE SHOWING THE WEIGHT AND COST PER FOOT OF CAST-IRON PIPE.

Diameter of bore. Inches.	Thickness of metal. Inches.	Weight of pipe per lineal foot. Lbs.	Cost of pipe per lineal foot. Cents.
1	¼	3.06	15
1¼	¼	3.67	18
1½	¼	4.29	21
1¾	⅜	7.81	39
2	⅜	8.73	44
2¼	⅜	9.65	48
2½	½	14.70	73
2¾	½	15.93	80
3	½	17.15	86

The weight of a cubic foot of cast-iron being 450 lbs., and the price being five cents per lb.

TABLE SHOWING THE CAPACITY OF McGOWAN’S DOUBLE ACTING PUMPS.

Explanation.			No. 1.	No. 2.	Time required to fill a 6600 gallons tank.
Stroke in inches,			5	8½	Hours.
Diameter of plunger,			2⅝	3⅛	Hours.
Area of plunger,			5.278 in.	7.70 in.	Small pump, No. 1.	Large pump, No. 2.
Cube of half stroke in gallons,			0.114	0.283	Small pump, No. 1.	Large pump, No. 2.
Discharge in gallons per hour.	At 10	Full strokes per minute.	136.8	339.6	49	19
	At 20		273.6	679.2	24	10
	At 30		410.4	1018.8	16	7
	At 40		547.2	1358.4	12	5
	At 50		684.0	1698.0	10	4
	At 60		820.8	2037.6	8	3½
	At 70		957.6	2377.2	7	3
	At 80		1094.4	2716.8	6	2½
	At 90		1231.2	3058.4	5	2¼
	At 100		1368.0	3396.0	5	2

CHAPTER XVI.
MANAGEMENT.

All that is required to render the efforts of railroad companies in every respect equal to that of individuals, is a rigid system of personal accountability through every grade of service.—D. C. McCallum.