in 1714, by the son of a Swedish Nobleman, who taught mathematics in Newcastle. "This powerful engine is now in common use in all the large collieries. As simplifiers of it, the names of Messrs. Boulton and Watt, as well as that of the ingenious builder of the Eddystone light-house, will be long remembered." When the last-named party, under the sanction of their patent, introduced the improved steam engines into the mining districts, they stipulated, after receiving a large price for the engines put down, to divide with the parties working them, the amounts accruing from the saving of fuel effected, as compared with the old machines; and so profitable was this arrangement, especially in Cornwall, where coal was dear, that one concern (the Consolidated Mines Company), using three powerful engines, paid to the patentees £2,400 per annum.

The pumps, of which there may be one or more in each pit according to circumstances, are of a size proportionate to the work to be done: sometimes they are 12, 18, and even as much as 24 inches in diameter. If there be two or three pumps or cylinders, as is sometimes the case, they are placed side by side, and supported at intervals by beams fixed across the pit; cisterns being placed at different elevations to which the water is raised, and if possible delivered off by an adit considerably below the surface: in some instances also, cisterns are placed at the level of feeders of water that occur at a distance of many fathoms from the bottom, and deliver some hundreds of gallons per minute, so as to save the waste of steam power which would be consequent on allowing this the self-acting engine had, till that time, been incumbered, and applied lever-rods for opening and shutting the cocks, which seemed to perfect the machine.

UNDERGROUND STEAM-ENGINES.

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water to fall to the sump, in order to raise it through the whole length of the pumps. The hydraulic action is exactly similar to that of a common sucking pump. The bucket in each cylinder consists of a stout rim of iron, surrounded with thick leather, and having a cross bar, to which are hinged two valves or clacks opening upwards: there is also a similar contrivance made stationary near the bottom of the pump. The rods or spears to which the working buckets are attached, are fastened with cottars on each side of a piece of wood, which is suspended by chains on the head of the engine beam, which projects through an opening in the engine-house, and over the pit it has a lug or bracket on each side, and which fall upon pieces of timber, and thus prevent the rods from sinking too low. To the upper part of its face the rods, as already stated, are suspended by a stout chain, exactly resembling in construction that inside a watch: occasionally, the more scientific contrivance for affecting the parallel motion, by means of iron rods, is adopted. In order to avoid the inconvenience resulting from the immense weight of the pump rods in very deep mines, as well as to serve other purposes, there have been instances of the erection of steam-engines 100 fathoms below the surface. Mr. Farey mentions an instance of an engine working underground in a colliery at Whitehaven in 1776. It was placed 80 fathoms beneath the surface, and worked a series of pumps disposed down the dip or inclination of the strata of coal, which was very rapid. The pumps lifted four fathoms each, from one to another, and were worked by one sliding rod from the engine. The intention of this disposition was to avoid piercing the floor, which

must have been done with a perpendicular pit, and thus have let much water upon the workings. The same authority adds :-" In many situations where the bed of coal dips suddenly, and if the strata beneath the coals be of a porous nature, it is of great importance to preserve the water-tight floor of the coal perfect, in order to prevent the passage of the water; and in all such cases the pumps must be placed on the slope of the strata, instead of in perpendicular pits." In the Alfred pit at Jarrow, there is a 30horse steam-engine erected at a depth of about 130 fathoms below the surface: it is used in raising the coals up a shaft which unites with the workings, carried out 45 fathoms deeper still: there is likewise at the profound depth indicated by these two shafts, another steam-engine, to draw the coals up an inclined plane that lies coincident with the dip of the

strata.

We may now proceed to describe the arrangements adopted for raising the coal. The erection of head-gear will depend much, not only upon the description of machinery to be employed, but also upon the number and shape of the corves intended to be used. In some of the Staffordshire collieries, two pits are sometimes sunk sufficiently near each other to be worked by the same gin or whimsey, one of the buckets or corves ascending, while the other is descending in a separate shaft. In certain situations of this sort, the erection over the pit-mouth is exceedingly simple and inexpensive, consisting sometimes of nothing more than an inclined piece of timber with a pulley at the end for the rope to pass over, and supported by wooden props, as represented in

* Treatise on Steam-Engine, p. 238.

ropes, or with cylindrical surfaces for flat ropes, are elevated beside one another in the upper part of a framework of timber over the mouth of the pit: the whole is rendered very substantial by buttresses applied on every side. In some collieries chains are used; they are reckoned more economical than ropes, but the links are more liable to snap without giving warning by appearances of wearing or otherwise, than is generally the case with ropes. A flat rope, con

near Sheffield, is in general use. The ropes or chains pass from the head wheels to the drum of the gin, or to a wooden cylinder, on the axle of a wheel worked by an adjacent steam-engine, upon which they are wound. The annexed cut represents the exterior appearance of one of the old-fashioned steam-engines, still very common about collieries, and called a whim, Fig. 25.