The results in drawing heavy freight trains were equally good with each fuel, the engine having at all times an abundance of steam on heavy grades, no smoke nor cinders, and no collection of cinders in the forward part of the engine.
The fireman arranged his fires at a station, and did little or nothing except to smoke his pipe and enjoy the scenery until he reached the next station. An incident occurred to prove that we were not playing with the machine. They told me one morning that we should be given a load of 25 per cent less than the maximum load of an engine of her class (30 tons). We started up the 100 foot grade, and found we could barely crawl, and our engineer got furious over it. He thought they were repeating a trick already attempted by screwing down a brake in ascending a grade. We detected it, however, and found a pair of wheels nearly red hot. Upon this occasion we found nothing amiss, except full cars where they had reported only a light load. We pulled to the top of the hill, the steam blowing off furiously all the time.
This was a new experience to the Italians, and might surprise some Americans. When we arrived at the station, the inspector-general and his corps of engineers were evidently amazed, and it was evident we had captured them. He said to me, "I can congratulate you, signor, on possession of a superb machine."
Afterward one of the engineers said to me: "Do not let it be known that I told you what you have hauled or I shall lose my place, but you have drawn 50 per cent more than the maximum load of one of our 40 ton engines." I said: "You attempted to 'stall' us, and when you try it again, be fair enough to give me a flat of pig iron, and as you pack cars on one end I will pack pig iron upon the engine until she will stick to the track, but rest assured that you will not be able to get that steam down." The experience with that engine proves conclusively to my mind that the general principles of steam making are the same for both stationary and locomotive practice. The grand secret of the success of that Wootten engine was the enormous area of the grate surface, being, if I remember correctly, 7 by 9 feet, permitting thin fires to be carried and complete combustion to be obtained before the gases reached the boiler tubes. An enormous crown sheet was presented, and that is where the bulk of the work of any boiler is done.
Thin fires accomplish this. As already stated, a given amount of coal generates a given amount of gas, and this gas requires a given amount of air or oxygen. This air must be supplied through the grate bars and then pass through the interstices of the mass of heated coal. It requires about 10 cubic feet of air to consume one cubic foot of gas. In stationary boilers we find that if we use "pea" and "dust" coal, an extremely thin layer must be used, or the 10 feet of air per foot of gas cannot pass through it; if "chestnut" coal be used, the thickness may be increased somewhat; "stove size" allows a thickness of six inches, and "lump" much thicker, if any wise man could be found who would use that coarse, uneconomical size. Of course, I am speaking of anthracite coal. Opinions differ about "soft coal," but the same general principle applies as regards an unobstructed passage of air through the hot bed of coal.
Now, it will be agreed that the locomotive of the future must be improved to keep up with the times. Fierce competition requires increased efficiency and reduced expenses. I am told by you railroad gentlemen that the freight business of the country doubles every ten years. Trains follow close upon each other. What are you going to do? Are you to double, treble, or quadruple your tracks?
It seems to me much remains yet to be done with the locomotive. We must burn a great deal less coal for the steam we make, and after we have made steam we must use that steam up more thoroughly. In the short cylinder required by locomotive service, the steam, entering at the initial pressure pushes the piston to the opposite end, and it then rushes out of the exhaust strong enough to drive another piston. Of every four dollars' worth of coal consumed, at least two dollars worth is absolutely thrown away. Or, of every ten thousand dollars spent for fuel, five thousand dollars are absolutely wasted. How can we save this? It would seem obvious that if steam rushes from the exhaust of an engine strong enough to drive another engine, the common sense of the thing would be to put another engine alongside and let the steam drive it, and we should get just so much more out of our four dollars' worth of coal. It seems evident that we must follow the lead of the steamship men, and compound the locomotive engine, as they have done with the marine engine.
Next we must attack the extravagant furnace, and increase its area and reduce the depth of the bed of coal. The difficulty of making this change seemed to me to be removed, on examining an engine on the Providence & Bristol Railroad, the other day. The machine was made at the Mason Works, of Taunton. It was an engine and tender combined, the truck being at the rear end of the tender, and the driver placed well in advance of the fire-box, so that the maximum weight of both engine and tender rested upon the drivers. In thus removing the drivers from the proximity of the fire-box, abundant facility is afforded for widening the fire-box, so as to obtain a grate area as large as that of the Wootten engine or of a stationary boiler. It seems to me the increase of grate area can be obtained only by widening; for a length of more than six or seven feet is very hard upon the fireman. You certainly cannot get more power by deepening present fire-boxes, except by an enormously increased waste of fuel, which all will concede is already sufficiently extravagant.
In arriving at the conclusion of these hasty and I fear somewhat incoherent remarks, I would say that the object aimed at for the improvement of the locomotive would be reached, first, by making steam economically, by employing such increased grate area as will permit running thin fires and moderate or comparatively slow draught; and, secondly, in economically using the steam which has been economically made by compounding the engine.
I have given you merely the views of an "outsider," who has had a somewhat extensive experience in stationary engineering, and who has observed locomotive practice in many parts of the world. These views are offered for what they are worth, as suggestions for future thought in designing engines, and as a sort of refresher upon rudimentary points which long familiarity with every-day phenomena causes us at times to overlook. I trust that your deliberations may aid in the speedy reduction of the expenses of transporting freight and passengers, for the benefit of the railroad companies and, in their turn, the advantage of the people at large.
Address before the June Convention of the Master Mechanics' Association.