_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.