The Screw.

139

Chap. 16.]

by windmills. But the outer cylinder is more generally fixed to theedges of the helix, and turned with it. It was made in this manner bythe ancient Romans ; the outer eylinder or case was of plank, well joint-ed together, and nailed to the edges of the screw, and the whole cementedwith pitch, and bound together by iron hoops. It was moved like thenoria, &c. “ by the walking of men.” Vitruvius , B. x, Chap. 11. SeeNo. 59.

The screw as represented in the preceding figures, has never been lostto the world since its invention, although it has long been unknown in thatcountry in which it was devised—Egypt . It appears early in printedbooks. In the first German edition of Vegetius , (1511) it is figured, andnearly in a vertical position. A laborer with a feather in his cap, and asword at his side, is seated across the top of the frame, and turns it by acrank. a

Like almost every other hydraulic engine, the screw has often beenre-invented. Cardan mentions a blacksmith of Milan, who imagining him-self its original inventor, “ for joy, ran out of his wits,” and the writerrecollects when a boy, hearing of an ingenious shoemaker in much thesame predicament. It appears to have been, like other machines for thesame purpose, mtroduced into England from Germany . “ The Holländ-ers, (says Switzer,) have long ago, as some books that I have seen oftheirs of fortification intimate, us’d them in draining their morassy andfenny ground, from whence they have been brought into England; and usedin the fens of Lincolnshire, Cambridgeshire and other low countries.Those of the smallest kind that are worked by men have only an ironhandle, as a grindstone has; but the largest that are wrought by horses,have a wheel like the cog-wheel of a horse mill. This engine, (he con-tinues,) which takes hold of the water, as a Cork screw does a cork, willthrow .up water as fast as an overshot wheel, whereby in a short time, aninfinite number of water may be thrown up; and I remember when thefoundation of the stately bridge of Bienheim was laid, we had some ofthem used with great success ; and they are also used in the New RiverWorks, about Newbury , Berkshire , and said to be the contrivance of acommon soldier, who brought the invention out of Flanders.” Hydros-tatics, 296, 298.

When employed to raise water to great elevations, a series of two,three, or more, one above another, have been employed; the lower onedischarging its contents into a basin, in which the inferior end of the nextabove is immersed, the whole being connected by cog wheels. Thus anold author observes, “ you may raise water to any height in a narrow place,viz. within a tower to the top thereof, as we have known done at Au-gusta, in Germany ; to wit, if the spiral pipes be multiplied, so that thewater being raised by the lower spiral, and being poured out into some re-ceptacle or cistern ; hence, it may be raised higher again by another spiral,and so successively by more spirals, as high as you please, all which spir-als may be moved by one power, viz. by the water of a river underneath,or by another animated pow'er.” Moxon.

It was one of the objects of the Marquis of Worcester, and his ‘ unpa-ralleled workman, Caspar Kaltoff,’ to avoid the necessity of thus combin-

a Whether sitting was the usual position of European laborers and mechanics whenat Work, in the middle ages, we know not; but Cambden has a remark which intimatesthat all English mechanics had not in his time, abatidoned this oriental custom In con-cluding his long account of “ the States and Degrees of England,” from kings, princes,“ ukes > lords, knights, &c. he continues, “ lastly, craftsmen, artizans or workmen; be they

at labor for hire, and namely, such as sit nt work, mechanicke artificers, smiths , car-penters,” Stc.