ers with the stacks set back or ahead three inches. If it had been three inches out sidewise it would have been noticed very quickly. Now if we have our diaphragm adjusted properly, our stack in line with the exhaust steam, and the engine is not sharp enough on her fire, raising the pipe or lowering the sleeve, or both, will increase her draft on the fire within certain limits. If then you do not get results the exhaust pipe from the air pump should be examined to see that it does not strike the flare on the pipe, or the steam pipes are leaking. If they are in good condition, as a last resort, you may have to decrease the size of the nozzle. But you should aim to run with as large a nozzle as possible, consistent with steam making, in order to reduce the back pressure in the cylinders. It is true that all engines will not steam alike, although they may have front end arrangements set the same. But if the flues are clean, and the stack and exhaust pipes are in line, you can use the adjustment of the best steamers as a guide to set the others by, and the changes necessary will be slight, providing the valve gear and cylinders are taking care of the steam after it is generated. A little study on this subject and the results obtained by the changes will make you familiar with the boiler and draft appliances. An old engineer said: "I have worked hard all my life but am afraid that I have not studied as much as I should have in my early days."

As we were on our way to the supply room we soon had an illustration. The store house had just taken in stock some new blizzard lamps for markers, with blue glasses. Two firemen were there, each with an order for green glasses for blizzard lamps, as green was the standard color for markers. The storekeeper said: "We have no green glasses, nothing but blue; they made a mistake and sent us blue glasses instead of green ones."

One fireman said that he did not want blue glasses and went away, thinking to get green ones from some engine in the shop. The other fireman said:

"Let me have a couple of the blue glasses and I will make green lights with them. Now that is a blue, but if I hold a yellow flame behind it, it will make a nice green light."

He tried it, and they did not send the glasses back. There was the illustration. The man that studied did not have to work as hard as the other fellow. We

then went to the paint shop and asked the foreman painter:

"If you wanted to paint something green and had no green paint, what would you do?"

The painter looked at us kind of green and said:

"I would mix yellow and blue to make green."

The engineer said: "I guess that fireman is all right."

It so happened that this engineer and fireman were sent out together on а freight engine. On arrival at a station where a stop was made for orders, the engine was stopped before passing a street crossing. While waiting for the "correct" to the order, the engineer asked to have the engine uncoupled from the train so he could run over the crossing and fill the tank with water. While waiting for the fireman, who was taking water, the engineer shut off the air pump throttle to fill the lubricator. The engine was equipped with a D-8 brake valve. After the lubricator was filled, in placing the valve oil can on the shelf, he moved the handle of the brake valve to full release position which allowed the train line to equalize with the main drum pressure, which was higher than the pump governor was set at. He then opened the pump throttle and the pump failed to start. At this time the fireman was just getting down into the cab, and the engineer asked the fireman to give him the coal hammer to tap the pump with and get it to work. The fireman looked up at the air gauge and told the engineer to make a reduction in the train line and he would not need the coal hammer. He made the reduction in the train line, when the governor opened and allowed the steam to get to the pump. This is very likely one of the questions that will be asked you in your air brake examination: "If your pump should stop working before the maximum pressure was obtained, what would you do?" Make a reduction in pressure that the governor pipe was connected to and see if the governor had not shut off the pump. It is also well to note that steam has a chance to get away from the pump after it has moved the piston to the end of the stroke. Failures have been known to occur to air pumps when the exhaust pipe was so arranged that the exhaust steam could be directed to the stack or the ground, due to the three-way cock being closed or if globe valves were used, both

being shut. Engines have given up trains or went back to the house on this account. This will apply to injectors when the main throttle is not sufficiently opened. The injector may get steam enough to work the heater, prime or lift the water, but not volume enough to force it into the boiler. If you happen to have an engine with a globe valve between the check and injector, see that it is open before reporting that the injector will not work. It is advisable to ascertain that there is proper opening for the

Fig. 1.

Fig. 2.

Fig. 3.

water to reach the injector, that there is steam enough from the boiler to the injector to force the water into the delivery pipe, and an opening in the check or boiler for the water to get through. If these three things are observed it will reduce the injector failures and repairs to same. These little things may save embarrassment, as it is not very pleasant to be called on to explain a failure if it could have been prevented.

While it is not necessary for an engineed to know how to set the valves on an engine, a great many of them do make changes in the length of the eccentric rods and improve the working of the engine. It is often found to be an advantage in case you are on a branch run away from the main shop. In order to become familiar with the construction of the valves and cylinders, and to trace the steam through the throttle valve, dry pipe, valve, steam passages, cylinders, exhaustpassage pipe, and the stack, you can easily fix this in your mind by cutting a valve and seat out of cardboard or wood, or marking the valve seat, steam ports, and exhaust port on paper and using the valve made of cardboard to move over the drawing. After you have made the drawing of the valve seat, cut your first valve to size as shown in Fig. 1 without lap. You will observe as you move this valve over the seat that as soon as one steam port is open for the admission of steam the other port is open to the exhaust cavity. This was the first form of the D slide valve, and steam followed the piston to the end of the stroke. In other words, each cylinder was filled with steam from the boiler twice every revolution. (You would not care to fire such an engine.) With a valve like this the eccentric was set at right angles to the pin.

One of the questions often asked is: "What is lap?" The answer is that it is the amount of valve that extends over the outside edges of the steam port when the valve is in the center of its seat. See Fig. 2. By cutting a valve as shown, you will now see that in order to have the steam port open when the piston is at the beginning of its stroke, the valve must be moved to the position shown in

Fig. 4,

Fig. 3, and given lead. Lead is the amount of opening of the steam port when the piston is at the beginning of its stroke. In order to get the valve in that position, you will have to change the position of the eccentric on the shaft. If the top and bottom rocker arms are of equal length, the large part of the eccentric should be moved toward the pin the amount of lap and the desired lead opening. With this valve having lap, the steam can be admitted to the cylinder for a portion of the stroke, when the valve closes the port or cuts off the steam. This is called the point of cut off. Now if the cylinders in each of the above cases were of 24-inch stroke, by applying the valve with the lap and cutting off the steam at 12 inches, or when the piston had moved 12 inches from the end of its stroke, we would have the steam confined in the cylinder to push the piston to the end of its stroke by its expansive force, without filling the cylinder its full length with steam taken from the boiler, thereby using one-half the steam that we would with a valve like that shown in Fig. 1. The advantage of lap is that you can work steam expansively. By studying this out and in making the sketch of the valve and seat

yourself, you can always retain it. It may come handy to you.

A man who had charge of a switch engine was asked what was meant by working steam expansively. He replied that if he put the lever down in the corner and pulled her wide open and ran as fast as possible that would be working steam expansively (expensively). The information sought was not to be obtained on that side of the engine, and the party went to the other side of the cab and asked how the steam got into and out of the cylinders. He was told that the steam went from the boiler to the front end of the cylinders when the engine was running ahead, and to the back end of the cylinders when the engine was backing up. This was not a very correct answer but he had never looked that matter up. He is on the right track, now, however, and working for promotion. He started to thinking and figuring for himself. After you get familiar with the D valve make a piston valve without side admission and observe how it works. You will find that no change is necessary in the eccentrics or valve motion if the steam is admitted by the outside edges of the valve opening the steam port. See Fig. 4. Think of it.

N° in

O other service affords the practice air braking as does the mountain grade, nor does any other hold equal possibilities of terrible disaster through "failure of the air brakes," that one time oft-used phrase for expressing that someone did not attend to his duty, an expression now pretty well relegated to the reporter on the daily paper.

For one competent to judge to be able to say of an engineer that he uniformly does good mountain grade braking, is to pay him the highest air brake compliment. But the mere fact that a man has worked on mountain grades does not necessarily carry with it any recommendation. Holding a train down a steep grade and holding it down safely are entirely different. Almost any engineer can do the former, many can do the latter, but too few do do it. However, in all justice it should be said that officials "winking" at the fast time made down steep grades by some man or men willing to take big chances, or who do not realize the danger this involves, forms an extenuating circumstance when it induces other more careful or better informed men to somewhat exceed the speed dictated by good judgment rather than subject themselves to an unfair comparison. At the same time, this does not excuse anyone for not having or using good judgment where so much is at stake.

The dangers of mountain grade braking may be divided into two kinds. First, runaways. Second, inability to stop

quick enough to avoid some sudden and unlooked for danger. These may again be divided as follows:

Runaways.

A runaway can occur while the air brakes are being used for the purpose of keeping the speed under control, and it can also follow an unwarranted dependence on the air brake to hold a standing car, cars or train on a steep grade.

Emergency Stops.

The safety of a moving train is measured by the distance that would be required to make an unexpected stop. All railroad men know that broken wheels, derailed cars, broken rails, couplers pulled out, burned or washed out bridges, slides, rocks, misplaced switches, errors in and forgetfulness of orders, inadequate flagging, etc., may at any time require a stop in a very short distance to avoid a bad accident, yet the speed often permitted by some down steep grades indicates a most serious lack of appreciation of the distance that would be required for stopping, or a most unwarranted and reckless trifling with danger.

In holding a heavy freight train down a steep grade the situation of the engineer can be illustrated by assuming the same heavy train on a level, behind it a locomotive capable of raising the speed of the train indefinitely, this engine working constantly at full power and in place of any means for shutting off or reducing this power, the engineer provided with nothing but the air brake to prevent the train