wonderful invention of yours, of raising water by fire, I was very desirous to enter into some discourse with you concerning the nature, use, and application of your engine, so strangely differing from all other engines ever yet invented for our works, and which, you positively affirm, will every way tend so much to our advantage in the use of them; and I do not doubt of meeting with that plainness, freedom, and good humour, that your discourse is generally accompanied with. And with the same freedom resolve me in such questions as the general sense of us miners may naturally propose to object against the use of your engine, especially such of us as are yet ignorant of its use and operation, who are more capable to judge of fact, than of the nature and power of that force which raises your water.

Author . Sir, I am extremely obliged to you for your freedom, and shall readily embrace all opportunities to inform and explain to you the true use and nature of my engine; and, therefore, desire you, with all imaginable freedom, to proceed and ask what questions you please, either as to your own thoughts, as well as what has been suggested to you by others. And you may be assured of a plain and candid answer to all your objections.

Miner . Then, sir, which way will you go to work with your engine to clear an old work full of water?

Author . Why, sir, to deal plainly with you, if your shafts are, or may be cut straight, your tub-engines, or chain pumps, may draw forth the water. And the charge, in that respect, is not to be accounted for, because no mine would be thrown up or neglected but on account of the feeders or springs, which being certain, and constantly to be carried off winter and summer, the prospect of being likely to succeed, makes your mine worth working or emptying within twenty feet of the bottom, if ever they were worth sinking, though you work or drain by the common way of tubs or chain-pumps. And could the constant charge of those engines be afforded, numbers of them will empty and keep under any work; but it is the constant charge of carrying off what the springs bring in is the chief thing to be considered in the business of mines, which constant charge is what we lessen very much by this engine of mine.

Miner . What signifies your engine then, sir, if it be not capable of sinking or forking an old mine?

Author . Hold, my good friend, a little patience; I have dealt plainly and impartially with you about the use of your old engines: and for my engine, it will clear an old work, if full of water, as readily as your tub-gins or chain-pumps, provided the shafts are good. The method I propose to clear an old mine, if sixty feet deep, and full of water, the feeders not above two-inch bore, which is done at a very small charge after this manner; viz. I fix my engine on the top of the mine, and only suck and deliver a three and a quarter inch bore; as soon as we have sunk the water as far as our suction will go, which will be some twenty-two, twenty-four, or twenty-six feet deep below the surface, there I make a room fit to receive another engine, which I fix with his force-pipe to go up to the top of the pit; and when I have sunk about twenty-four or twenty-six feet more, then I fix a smaller engine of two inches bore, which, sucking twenty, and forcing forty, does your work and keeps all safe; or let your small engine be kept at work, while you remove the larger engine from the top to the middle station, and then you will have occasion for no more than two engines, the greatest of which may be removed as soon as the smaller is fixed in the lowest or proper station. And that you may be convinced of my impartiality, it is my opinion, that in gaining an old work, or sinking a new one, you use your old engines of tub or chain-pumps: this engine of mine being most proper, when you are come fairly to the bottom either of the ore or coal; for then, if you have but one lift, one station or engine-room will be sufficient. And by having two sumps or bottom cisterns, your water may, in some measure, settle in one of them in its passage to the other. So that the miners working tolerably clean, and suffering as little dead or loose coal or ore as is possible to mix with the water, you may have the water to draw only a little discoloured; for you know, as well as I, that generally the water coming from mines or coal-pits, while they work by the gins now in use, is almost clear water.

Miner . Sir, I thank you for your candour in relation to the clearing of an old work. But supposing that our water arises thick and muddy, which you know will sometimes happen, what shall we do with your engine then?

Author . What you say, sir, I know to be very true, that sometimes you have thick, muddy gravel and nasty water. To prevent which from coming into, or offending our pipes, we have a frame of board made full of holes round about the bottom of our pipe that receives the water, for sluge or fine dirt it will do my engine no injury. Indeed, the clearer our water is in our boilers the better it is for our work; but for our receivers and their clacks you may clear them as you work it from stones, coal, ore, or any other annoyance, though hung in the very clack; for by emptying of one or both the receivers of their water, you cause the motion, either of suction or force, immediately to be so strong, as to clear and blow out all before it to the top of the pit; insomuch, that I have found filings of copper, large bits of metal, considerable quantities of coal and stone, delivered and thrown up with water out of my engine above sixty feet high. However, clear water is preferable before the dirty water in the work of mine engine.

Miner . But, dear sir, if sixty, seventy, or eighty feet be the determinate height for raising of water by your engine, how shall we use your engine in a mine or pit that requires water to be raised three times eighty feet, as you know some of our works do.

Author . I heartily thank you, sir, for this last proposal, because I have now an opportunity to acquaint you, that the force used in my engine is in a manner infinite and unlimited, and will raise your water five hundred or one thousand feet high, were any pit so deep; and that you could find us a way to procure strength enough to support such an immense weight, as a pillar of water a thousand feet high must certainly produce. However, to give you an answer, I must entreat you to give my engine as kind entertainment and fair quarter as you do to your engines now in use: for, I am sure, you are not ignorant of a custom used in very deep mines, (in several parts of England,) of raising their water by several lifts, from cistern to cistern, to a very great height, although some of their lifts may not be above twelve, sixteen, or twenty feet a lift at the most. And suppose that your engine now in use at twenty feet the lift, and my engine at sixty, seventy, or eighty feet, for at any of these lifts we raise a full bore of water with much ease, then one lift of my engine at sixty feet answers to three lifts of your engines at twenty feet, and also to four of your lifts at eighty feet, &c., which you may please to take for a sufficient answer to your last objection. I have known, in Cornwall, a work with three lifts, of about eighteen feet each lift, and carrying a three and a quarter inch bore, that cost forty-two shillings per diem, reckoning twenty-four hours the day, for labour, besides wear and tear of engines; each pump having four men working eight hours, at fourteenpence a man, and the men obliged to rest at least one-third part of that time.

Miner . You have, sir, hitherto given me undeniable answers to my former objections, for which I thank you; but I fancy I shall puzzle you, when I ask you how you will manage your engine to draw up our water, where the shafts are not direct, but turn and wind to and fro?

Author . Sir, this last question is so far from being any hardship put upon my engine, that no engine ever