326
[Book III,
over the cylinders. The axle of the beam is continued through both sidesof the wooden case, and to its squared ends two iron rods are fitted, likecrank handles on the axles of grindstones. To the lower ends of theserods are attached, by bolts, two horizontal bars of wood, on the outside ofwhich a number of long pins are inserted, as shown in the cut. Whenthe engine was in use men laid hold on these pins, one man to each, andpushed and pulled the bars to and fro, somewhat as in the act of rowing,and thus imparted the requisite movement to the pistons: a mode of work-ing fire-engines that might, we think, be adopted with advantage in mo-dern ones ; for the vigorous working of these is so exhausting, that thestrongest man can hardly endure it over a minute at a time. The jet pipeof this engine is connected to the other by coupling screws or “ Unionjoints,” the most useful and ingenious device for joining tubes that ever wasinvented; and one which, from its extensive application in practical hy-draulics, in gas and steam Works, and also in philosophical apparatus, hasbecome indispensable. We notice it here on account of its having beenerroneously attributed to a modern engineer; whereas it was not newwhen introduced into Ypres fire-engines above a hundred years ago.
Two of the greatest improvements ever made in these machines wereintroduced about the same time, viz : the^air chamber and flexible pipesof leather and canvas ; upon these principally the efficiency of modernengines depends. By the former the stream ejected from a single pump isrendered continuous ; and by the latter, it is no longer necessary to takethe engine itself into, or close to, a building on fire ; where in most casesit is impossible, from the heat of the flames and from smoke, to use it witheffect. The modern author, or rather introdueer, of the beautiful devicefor rendering the broken or interrupted jets of old engines uniform, is notknown. In accordance with the customs of the age, he probably kept itsecret as long as he could. We suspect that Hautsch’s engine was fur-nished with an air chamber, and that it was on that account chiefly that hewas so anxious to prevent its construction from becoming known. Beck-man States that Hautsch used a flexible pipe to enable him readily to changethe direction of the jet, “but not an air chamber, which Schottus certainlywould have described,” How Schottus could have done this, when ac-cording to Prof. B. himself, Hautsch refused to let him see the interior ofthe engine, it is diffieult to imagine ; and unless he had been acquaintedwith the properties of an air vessel, had the engine even been thrown opento his inspection, he could hardly have comprehended its action, unlessexplained to him by the manufacturer; at any rate, the secret, if it was inHautsch’s possession, was not long after divulged ; for in 1675 an anonymmous writer in the Journal des Scavans figured and described an enginewith this appendage, The account was the same year translated and pub-lished in volume xi of the Philosophical Transactions , p. 679. As thisis the earliest notice of the application of an air vessel to pumps in moderntimes that we have met with, it is entitled to a place here.
“ This engine [No. 147] is a ehest of copper, pierced with many holesabove, and holds within it the body of a pump whose sucker is raised andabased by two levers. These levers having each of them two arms, and eacharm being fitted to be laid hold on by both hands of a man. Each leveris pierced in the middle by a mortaise, in which an iron nail [bolt] whichpasses through the handle [rod] of the sucker, turns when the sucker israised or lowered. Near the body of the pump there is a copper pot,I, [air vessel] joined to it by the tube G, and having another tube K N L,which in N may be turned every way. To make this engine play, wateris poured upon the ehest to enter in at the holes that are in the cover