Q. Should the engineman run by the glass gage or by the cocks?

A. By neither alone. Either can give false indications. The one checks the other.

Q. Why does the water-level rise when the throttle is opened?

A. Because pressure is taken from the water, and the steam forms in greater quantities, lightening it.

Q. How can water be found in the boiler if the water drops below the bottom gage-cock?

A. By suddenly opening the throttle or blowing the whistle.

Q. When an engine is foaming badly, how must the true water-level be found?

A. By first shutting off steam.

Q. Which gage-cock is it most important to keep open and in perfect working order?

A. The lower one.

Q. Does water remain at the same level when the throttle is shut off?

A. No.

Q. What is the least depth of water on the crownsheet that is safe?

A. One gage.

Q. How much water on the crown-sheet with one, two, and three gages respectively?

A. Usually the gages are three inches above the sheet and between each other.

Q. Do you consider it safe to run an engine with one or more of the gage-cocks stopped up?

A. No.

Q. Is the water-glass safe to run by if the water-line in the glass is not moving up and down when the engine is in motion?

A. No.

Q. If you were stopped on the road and found your water dropped out of sight, how would you try to raise it.

A. By opening the blower or the throttle, so as to make something like working conditions.

Q. Suppose that would not raise it to a safe hight, what would you do?

A. Deaden, draw or dump the fire.

Q. What should be done in case of failure of the water supply in the tender?

A. The train should be left and the engine and tender run to a water-tank, unless there was some stream, pond or other source of water that might be used.

Q. What should be done in case the water in the tender got low, in time of snow blockade?

A. The tender should be filled with snow, and this melted by the heaters.

Q. What should be done in case of the tank-valve getting off its stem and dropping into the seat so as to keep the water out of the hose?

A. The heater should be put on with full force for an instant, to drive the valve off the seat.

Q. Why not keep it on?

A. For fear of bursting the hose.

Q. How rapidly should water be supplied to the boiler?

A. As a rule, on levels, at the same rate at which it is evaporated; where, however, an up grade is to be taken, the feed should be shut off at the crest the injector may be put on to prevent over-steaming. If there is a down grade following, more feed may be put on than if there is a level at the top of the grade.

Q. Can a boiler explode if full of water?
A. Yes; especially in starting out.

Q. Is injecting feed water on heated plates liable to cause an explosion?

A. No.

Q. What would be likely to take place?

A. Leakage at the seams.

Q. Describe the Sentinel low water alarm.

A. This is an appliance, mounted on the fire-box roof, and consisting of a small whistle in connection with the steam space, and the valve of which is operated by the expansion of a nearly horizontal pipe in communication with a vertical pipe reaching down to the level at which it is desired to give an alarm. Normally, this latter pipe is sealed and the expansion pipe is at a temperature under that of the usual steam in the boiler. If, however, the water level falls and unseals the vertical pipe, steam enters and expands the other one, which opens the whistle valve.

CHAPTER XXIII

THE WATER

Q. What is a bad effect of blowing out when hot?
A. Baking on mud or other foreign substances.

Q. How should a boiler be cooled down quickly?

A. By blowing off the steam and replacing it with cold water; then replacing the warm or hot water in the shell with cold. Or, running down 'two gages under forty pounds of steam, then cooling down gradually.

Q. What is an occasional source of grit in the water? A. Holes in the tank top, through which cinders and coal may fall and clog the strainers.

Q. How can heavy mud deposits best be prevented? A. By frequent washing only.

Q. How may water for locomotives be treated for carbonate of lime, sulphate of lime, and sulphuric acid? A. By lime and soda ash.

Q. What is sometimes the effect of this treatment? A. To cause the boilers to foam.

Q. What are the usual effects of limy water?

A. Leaky heating-surface, and incrustations.

Q. How may leaky flues or stay-bolts be cured temporarily?

A. By putting bran or potatoes in the feed-water, care being taken not to put in enough to cause foaming, and not to depend on it longer than to get home with.

Q. What is a good practical test of whether water in a tank is good enough for boiler-feeding?

A. If it curdles instead of making a lather with ordinary soap, it is too hard for boiler use, and should not be employed if any other can be had within reasonable distance, and in sufficient quantity.

Q. Do difficulties with bad water increase or decrease with the pressure?

A. They increase; with low-pressure there is practically no difficulty in washing out the sediment. With high pressures the temperature of the water delivered by the injector is sometimes so high that scale is deposited in the check valve and delivery pipe and in the injector delivery tube.

Q. Is there any one dope or compound that is a good antidote medicine for any and every sort of water?

A. No; a material, either simple or compound, that would be beneficial in the case of one kind of water might be inert when used with another; or might indeed be deleterious.

Q. What compound seems to be good for more kinds of water than any other?

A. Tannate of soda.

Q. Does the character of the water vary from season to season?

A. Yes; especially in districts where the melting snow or heavy rain dissolve out the soluble salts in the soil and carries them to the source of the station water. The composition of the water may even change from day to day.

Q. Are there any other sources of undesirable substances in the feed water than those furnished by Nature?

A. Yes; factories sometimes discharge, either regularly or occasionally, dye solutions, sludge, etc., that eventually find their way into the tender tank unless eliminated by filtering or chemical neutralization.

Q. Can chemical neutralization make such contaminated water even worse?

A. Yes, unless the resultant insoluble new compounds are filtered out before they reach the station tank or the the tender.