Micrographia restaurata: or, the copper-plates of Dr. Hooke's wonderful discoveries by the microscope, reprinted and fully explained. Whereby the most valuable particulars in that celebrated author's Micrographia are brought together in a narrow compass; and intermixed occasionally, with many entertaining and instructive discoveries and observations in natural history ... / [Robert Hooke].

  • Hooke, Robert, 1635-1703.
Date:
1745
Catalogue details

Licence: Public Domain Mark

Credit: Micrographia restaurata: or, the copper-plates of Dr. Hooke's wonderful discoveries by the microscope, reprinted and fully explained. Whereby the most valuable particulars in that celebrated author's Micrographia are brought together in a narrow compass; and intermixed occasionally, with many entertaining and instructive discoveries and observations in natural history ... / [Robert Hooke]. Source: Wellcome Collection.

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    An Explanation of the Third Plate. F t 0. x. The Sparks of Fire ftruck from a Flint and Steel. IN the common Way of ftriking Fire with a Flint and Steel, fiery Sparks fly out at Globules of every Blow ; which Sparks are nothing more than fmall Pieces of the Flint or Steel, Stec]* (but ufually of the Steel) broken off by the Violence of the Stroke, and either melted inftantaneoufly into Steel Globules, or made at leaft red-hot, and thereby capable of kind¬ ling Tinder or Touch-wood. The Heat is likewife fo intenfe fometimes as even to vitrify the broken Particles. As a Proof of this, Dr. Hooke ftruck Fire over a Sheet of very white Paper, and ob~ ferving diligently where the Sparks feemed to vanifh, he difcovered there certain very fmall, black, but glittering and moveable Specks, which, when examined with his Mi- crofcope, appeared to be little round Globules; fome whereof did, from their Surface, yield a very bright and ftrong Refle&ion on that Side next the Light, and refembled Iron- Balls. One of which, whofe Surface was pretty regular, is (hewn by the Letter A. He perceived in this the reflected Image of the Window, and alfo of a Stick, which he moved up and down between the Light and it. He found others almoft regularly round, as to the Bulk of the Ball, but with rough unpolifhed Surfaces; which rendered the Refledion from them much more confufed and faint. Such are reprefented by the Letters B, C, D, E. Some were cracked or cleft, as C; others broken and quite hollow, as D; which feemed like half the hollow Shell of a Granado, broken irregularly in Pieces. There were other different Shapes; but that in particular, marked with the Letter E, was a larger Spark of Fire than ordinary. It went out on one Side the Flint employed in ftriking it, and ad¬ hered thereto by the Root F. On the Top of its Stem was faftned half an hollow Ball, with the Mouth of it opening upwards; fo that it appeared fomewhat like a Funnel, or a Rummer-Glafs without a Foot. The melting oP the Particles of Steel, inftantaneoufly, upon the Collifion, is very wonderful, and comes up nearly to the Effeds of Lightning : Indeed there feems to be in Iron or Steel a fulphureous combuftible Matter very eafily put in Adion ; for either ham¬ mering, filing, or rubbing it with Violence, will prefently make it fo hot as to be able to burn one’s Finger: And if the Filings of Iron are only let drop through the Flame of a Candle, (placing a Sheet of white Paper underneath, to catch them for Examination) many of them will be found melted even by that fudden Tranfit, and appear remarkably (hining to the naked Eye; and if we view them farther by the Microfcope, we (hall foon be fatisfied they are exadly fuch round Globules as are formed by ftriking Fire with a Flint and Steel. As obtaining fuch minute Globules as thefe, of Lead or Tin, and that, even in Quan- Globules of tity, eafily and quickly, may be'defirable by fome, we (hall here fubjoin the Way ofLead or 're¬ forming them, which Dr. Hooke fays a learned Phyfician taught him. Reduce the Metal you would fhape thus, into exceedingly fine Filings : for the fmaller your Filings are, the fmaller will be your Globules. Strew fome fine and well-dried powder of* Quick-Lime at the Bottom of a Crucible, on which fcatter fome of your Fil¬ ings very thinly j then drew on more Powder, on that again more Filings, and fo alter¬ nately, Stratum fuper Stratum, till you have filled your Crucible, in fuch a manner, that, as near as may be,A no two Filings may touch each other. Place the Crucible in a gra¬ dual Fire and increafe the Heat by Degrees, till it be fufikient to make all the Filings mix’d with the Quick-Lime melt, and no more. For if the Fire be too hot, many of the Filings will join and run together: But if the Heat be duly proportioned, upon walking the Lime-Duft in Water, all thofe fmall Filings of the Metal will fubfide to the Bottom, in a moft curious Powder, confiding of Balls or Globules exadly round; which, if very fine, is excellent for Hour-Glades. One may at any time, procure immediately minute Globules of Lead, by only Globules of kindling a red Wafer, fuch as Letters are fcaled with, at a Candle; for as it burns (and Lead- it will not go out till it be wholly confumed) the red Lead employed in the Colour¬ ing melt% and falls down, in regular minute Globules j which, if a Sheet of dean C wh:te