steam pipe could be carried there from a boiler on the surface. In fact I had no other recourse, as, if I put a boiler in the mine, I would have to use part of the old workings for a smoke stack, but as that was going to 'cave,' I would then have had no smoke stack at all, so I resolved to carry the steam 1,300 feet, which was the shortest available distance to the surface. I had no data to work on other than the knowledge that, in some coal mines in the north of England, they have carried steam six or seven hundred feet for accessory work, from lower levels than the main pumping level. It was 'Hobson's choice' with me, but I was fully aware that I staked my reputation in the experiment.

"The boiler was of the common Mississippi style-two flues of 42 inches diameter 26 feet long, and two flues 14 inches diameter, having also steam and mud drums. The steam was taken from the steam drum and passed through a superheater under the boiler-the same firing answering for both and thence through a 4 inch gas pipe down an air shaft to the lower tunnel, where I had fixed an expansion joint and also an accumulator; this was a small boiler, 30 inches diameter and 5 feet long-its object being to catch water in case the boiler should foam, or to drain the pipe beyond. As the pipe raised gradually from this accumulator to the engine, with the grade of the tunnel, it was in just the right place. The length of the steam pipe in the air shaft was 201 feet. From the ac

cumulator the pipe ran alongside of the tunnel, to a branch tunnel, to the engine room-600 feet long--in the branch tunnel-500 feet long-and up a slight incline to engine room, 40 feet moremaking, in all, a steam pipe of 1,341 feet in length. In the engine room was placed another accumulator, the same as the one at the bottom of the air shaft, but set on its end-the steam going in at its middle and out to the engine at the top. The object of this one was to catch whatever water might be carried with the steam, also scale from the iron pipes, and to form a kind of reservoir for steam; as the engine had a variable cut-off on, it acted as such to a considerable extent. On each of the accumulators, was placed one of Furman's steam and water traps, also a gage to note pressure.

"The engine was made at the Vulcan Iron-works n San Francisco, and was a horizontal cylinder of 14 inches bore, 30 inches stroke, and was used cutting off a half stroke. It hoisted a bucket for sinking purposes, holding one ton of rock, in one shaft 200 feet deep; in another shaft a cage, with car and load weighing 3,000 pounds. The speed of hoist was 400 feet per minute; it also worked a pump of 8 inch bore, 4 feet stroke, with its machinery in the third shaft. The amount of water was not much-about half the capacity of pump, as the pump was going sucking about half the time. The trips of hoisting were made about every ten minutes, respectively-sometimes both

were hoisting together. The hoisting apparatus was of the friction variety-the same as generally used in these mines; in all I think the engine had to do about 35 horse-power of work.

"The steam pipe was 4 inch gas pipe screwed together with flanges at intervals of 100 feet. For convenience of repairs, in every 400 feet there was an expansion joint. The pipe was anchored to the side of the tunnel in the middle of that distance, so that it expanded both ways from that point. The casing of the pipe was of wood, made of two by 12 inch plank-making a box of eight inches square inside, in the centre of which rested the pipe on saddle pieces, the balance of space being filled with common wood ashes. The expansion of the pipe was very nearly two inches per 100 feet, from 60° to temperature of the steam at 80 pounds pressure. [325°.] The difference in pressure at the boiler from that at the engine, could not be detected; I changed the gages (Ashcroft's) from the boiler to the engine, but no difference could be found. I even made two gages of gas pipe, half-inch, of common siphon shape, and filled them with mercury. I made them long enough to suit our working pressure, and still no difference in pressure between boiler and engine. I also made experiments without the superheater, and found no difference in pressures. The only loss was an increase in the amount of water trapped off from the pipes. The

loss would then be one cubic foot per hour trapped off; with the superheater the loss was one third of a cubic foot per hour. The amounts trapped off were accurately kept; these figures are the average, and not the result of any one hour, although it never varied much from what is given. When the flow of steam through the pipes was rapid it was less; when slow, greater.

"The fuel was common pine wood, using from three and a half to four cords per twenty-four hours-which will compare with any engine having short steam pipe and doing the same amount of work with the same kind of fuel. The engine ran in the mine over one year, during which time I made numerous experiments with it. It is now out of the mine, as they have no use for it in there. It was a complete success, as it did more than was ever expected of it, and enabled the company to declare dividends during the 'caved' condition of their mine.

"In conclusion, I would state that, as far as my experiments went, I see no end to the distance to which steam can be carried-it being merely regulated, more by the amount of condensation than by difference of pressure. I would not hesitate to carry it one mile, if I could cover the pipe well-that being the great point to be looked after."

CHAPTER XXX.

PACKING STEAM PISTONS.

ECONOMY in fuel, saving in repairs, in short increased duty generally, results from well-packed steam pistons. Erroneous views respecting the performance of this duty prevail among engineers. It is thought necessary to use great force to insert the springs; the springs themselves have set screws in them, they are tremendously thick and heavy, entirely disproportionate to the work, and, in most cases, not what they should be. The surface of a steam cylinder is one of the most critical or nice points of the engine; when it is once ruined heavy expenses are incurred in renewing it; and since it can only be injured by gross carelessness, it behooves every engineer at all anxious for his reputation to be sure that he does not omit any portion of his duty toward it.

When the piston has been removed from the cylinder from any cause, the utmost caution should be observed in replacing it. Not only should the rings themselves be chalked before the follower is removed, so that they may occupy the same place in the cylinder, but every minute speck of dust, and the little concreted balls of tallow and sedi