The first thing is to fix the engine in a good double furnace, for contrived that the flame of your fire may circulate round, and incompass your two boylers to the best advantage, as you do coppers for brewing.
Before you make any fire, unskrew O and N, being the two small gauge pipes and clacks belonging to the two boylers, and at the holes, fill L, the great boyler two thirds full of water, and D the small boyler quite full.
Then skrew in the faid pipes again as tight as possible. Then light the fire at B No.1. When the water in L boyles, the handle of the regulator marked Z, must be thrust from you as far as it will go, which makes all the steam rifting from the water in L, pass with irriftible force through O No.1 into P No.1 pushing out all the air before it, through the clack R No.1 making a noise as it goes.
And when all is gone out, the bottom of the veffel P No.1 will be very hot. Then pull the handle of the regulator to you, by which means you stop O No.1 and force your steam through O No.2, into the P No.2 until that veffel has discharged its air through the clack R No.2 up the force pipe.
In the meantime, by the steams condensing in the veffel P No.1, a vacuum is created. So that the water must and will necessarily rise up through T the sucking pipe, lifting up the clack R No.3 and filling the veffel P no.1.
In the meantime the veffel P No.2 is being emptied of its air, turn the handle of the regulator from you again, and the force is upon the surface of the water in P No.1, the which surface being only heated by the steam, it does not condense it, but the steam gravitates of preffers with an elastic quality like air, still increasing its elasticity or spring, till it counterpoises, or rather exceeds the weight of the water ascending in S, the forcing pipe. Out of which the water in P No.1 will be immediately discharged when once gotten to the top, which takes up some time to recover that power;which having once got, and being in work, it is safe for any one that never saw the engine, after an half an hours experience, to keep a constant stream, running out thefull bore of the pipe S.
For on the outside of the veffel were transparent. For as far as the steam continues within the veffel, so far is the veffel dry without, and for very hot as scarce to endure the least touch of the hand. But as far as the water is, the faid veffel will be cold and wet, where any water has fallen on it; which cold and moisture vanishes as far as the steam, in its descent, takes place of the water.
But if you force all the water out, the steam, or a small part thereof, going through RNo.1 will rattle the clack for as to give sufficient notice to pull the handle of theregulator to you; which at the same time begins to force out the water from P No.2 without the least alteration of the stream; only some times the stream of water will be somewhat stronger than before.
If you pull the handle of the regulator, before any confiderable quantity of steam be gone up the clack R No.1. But it is much better to let none of the steam go off, (for that is but losing so much strength) and is easily prevented, by pulling the regulator some little before the veffel forcing is quite emptied. This being done, immediately turn the cock or pipe of the cistern X on P No.1so that the water proceeding from X through Y (which is never open, but when turned onP No.1 or No.2 but between them, is tight ans stanch) I say, the water falling on P No.1causes by its coolness the steam (which had such great force just before) to its elastic power, to condens, and become a vacuum, or empty space. So that the veffel P No.1is by the external pressure of the atmosphere. or what is vugarly called suction, immediately refilled, while P No.2 is emptying; which being done, you push the handle of the regulator from you, and throw the force on P No.1, pulling the condensing pipe overP No.2 causing the steam in that veffel to condense so that it fills while other empties.
The labour of turning these two parts of the engine, the regulator and water cock, and tending the fire, being no more than what a boys strength can perform for a day together, and is easily learned as their driving of a horse in a tub-gin: Yet, after all I would have men, and those too most apprehensive, employed in working of the engine, supposing them more careful than boys.
The difference of this charged is not mentioned or accounted of, when we confider the vast profit which those who use the engine will reap by it.
The ingenious reader will probably here object, that the steam being cause of this motion and force, and that steam is but water rarified. The boyler L must on some certain time be emptied, so as the work of the engine must stop to replenish the boyler,or endanger the the burning out, or melting the bottom layer of the boyler.
To answer which, please observe the use of the small boyler D. When it is though fit by the person tending the engine to replenish the great boyler (which requires an half and hour , or two hours tome to the finking one foot of water) then, I say, by turning the cock of the small boyler E, you cut off communication between S the great force pipe, and D the small boyler, by which means D grows immediately hot, by throwing a little fire into B No.2 and the water into which boyls, and in a very litle time it gains more strenght than the great boyler.
For the force of the great boyler being perpetually spending and going out, and the other winding up, or increasing it is not long before the force in D exceeds that in L; so that the water in D, being depressed in D by its own steam or vapor, must necessarily rise through the pipe H, opening the clack I, and so go through the pipe K into L, running until the surfaces of the water in D is equal to the bottom of the pipe H.
Then steam and water going together, will by a noise in the clack I, sive sufficient assurance that D has discharged and emptied itself of the bottom. And as from the top of D to the bottom of its pipe H, is contained about as much water as will replenish L one foot. So you may be certain L is replenishable one foot of course. Then you open the cock I, and refilled D immediately. So that here is a constant motion, without fear of danger of disorder, or decay'.
If you would at anytime know if the great boyler L, be more than half exhausted, turn the small cock N, whose pipe will deliver water, if the water be above the level of its bottom, which is halfway down the boyler; if not, it will deliver steam. So likewise G will show you if you have more or less than eight inches of water in D, by which means nothing but a stupid and willful neglect, or design, carried on for some hours, can any ways hurt the engine. And if a master is suspicious of the design of a servant to do mischief, it is easily discovered by the those gauge pipes:
For if he comes, when the Engine is at work, and find the surface of the water. such a servant deserves correction, tho' three hours after that, the working on would not damage or exhaust the boyler:
So that in a word, the clacks being in all water-works, always found the better, the longer they are used. And all the moving parts of our engine, being of like nature, the furnace being made of sturbridge, or fire-stone; I do not see if possible for the engine to decay in may years; For the clacks, boxes, and Regulator and cocks, are all old brass; and the veffels made of the best hammered copper, of the sufficient thickness to sustain the force of the working the engine.
In short, the engine is for naturally adapted to perform what is required, that even those of the most ordinary and meanst capacity, may work it for some years with out any injury, if not hired or employed by some base person on purpose to destroy it. For after the engine is once fixed, and at work, I may modestly affirm that the adventurer, or supervisor of the mine, will be freed from that perpetual charge, expenses and trouble of repairs, which all other engines ever yet employed in mines for the raising of water, are continuably liable unto.