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father; takingcare, that the Whole be demon-strated in such a plain and easy Manner,that it may justly be said to be adapted tothe meanest Capacity, though founded up-on an exact System of natural 'Philosophy ;so that a proper Regard is to be taken, thatnothing is asserted, but what' may, and ismade evident from the dame Principles.

"\dly, All the Branches of the mechanicalPart of Mining, or the various Ways of work-ing under Ground, must be expressed andparticularized, and made as clear as possi-ble ; the different Methods of differentCountries must be set forth ; for from everyone of them something may be collectedtowards improving our own ; therefore wemust not forget to mention the Tools,which, with all curious under GroundStructures, must be delineated upon Cop-per Plates.

4 thly, Draughts of all Machines apper-taining to Mine-works, must in like man-ner be exactly exhibited upon CopperPlates : In this Branch we need not beashamed to borrow from Foreigners ; a-mongst those that have been invented by theSwedes, we shall find a great many worthyof our Observation; for, in my Opinion, theyhave exceeded all I have ever seen by otherNations, particularly in one, which, in all Re-spects, answers the End in a very surprisingManner, without the Assistance ofRopes; as is

particularly