430
Century of Inventims.
[Book IV.
famous machine of the kind exhibited in the Borghese villa, which couldnot bave escaped his notice. It is described by Blainville as “ very art-fully contrived; and strangers, who are not acquainted with the trick, areinfallibly caught as in a trap when they are prevailed upon to sit in it.”Travels, vol. ii, p. 35. We shall notice a few more : “A little engineportable in one’s pocket, which placed to any door, without any noise butone crack, openeth any door or gate.” A similar device is quoted byWilkins from Ramelli, thus: “A little pocket engine wherewith a manmay break or wrench open any door.” (Math. Magic, book i, chap. 13,first published in 1648.) Again—An instrument whereby an ignorantperson may take any thing in perspective as justly and more than the skil-fullest painter can do by the eye.” Probably the Camera obscura, whichBaptist Porta had described, about a Century before, in his Natural Magic.See page 364 of the English translation of 1658, and also Fludd’s NaturalSimia seil Technica, 1618, page 308, for another mode. No. 29 of theCentury relates to “A moveable fortification—as complete as a regulär one,with half-moons and counterscarps.” Such a one is figured in Fludd’sSimia. It is of a triangulär form, with breast works and cannon rangedalong two sides. The whole is made of thick timber clamped together,and moved by horses, which are yoked to a long pole or mast, also sup-ported on wheels and attached to the rear or base of the triangle, so asto be out of the reach of shot from the enemy. The horses have theirfaces to the fortification, just as if yoked to the pole of a common carriageand fronting it—or, according to the old saying, “ the cart is put beforethe horse.”
His modes of discoursing by knotted strings, gloves, sieves, lanterns,&c. are similar to others mentioned in the Natural Magic of Porta, and inother works. Wilkins’s Secret and Swift Messenger also contains muchcurious information on such subjects. Several numbers of the Centuryrelate to repeating guns. These, as is well known, exercised the wits ofinventors long before his time. Porta, in his Magic, book xii, speaks of“ great and hand guns, discharged ten times” although loaded but once.They are even of much older date. Sometimes several barreis were joinedtogether. The “ arithmetical instrument, whereby persons ignorant ofarithmetic may perfectly observe numerations and subtractions of all sumsand fractions,” was in all probability the abacus, or Chinese sv>an-pan, nowused in schools.
Flying and diving, also mentioned by him, have occupied the ingenuityof inventors in every age. Cornelius Drebble constructed a diving-vesselwhich was pröpelled by oars worked through openings in the sides. Shortconical tubes of leather, through which the oars were passed, were con-nected to the openings so as to exclude the water; hence the joints some-what resembled those of the feet of a tortoise when protruded from theshell. The vessel was lowered by admitting water, and raised by pump-ing it out. (The distance of diving-vessels below the surface is easily andaccurately ascertained by a curved tube containing a little mercury, oneend being within the vessel and the other without.) Charles, Landgraveof Hesse Cassel, hearing of Drebble’s diving-ship, requested Papin tocontrive one. Papin’s machine is figured and described in the Gentlemän’sMagazine for 1747, page 581. Drebble’s vessel did not require a constantsupply of fresh air, for he had, or pretended to have, an elixir in a smallvial, a few drops of which restored the vitiated air so as to make it againfit for respiration. Something of this kind was known even before Dreb-ble’s time, if we may judge from one of several illustrations of diving inthe old German translation of Vegetius , A. D. 1511. A man clothed m