WITH NOTES. 425 



a weight&quot; under such circumstances, nevertheless, take 

 up &quot; two hundred pounds,&quot; that is, including the water. 

 A very similar kind of piston to the one here shown, 

 is suggested by Fludd, Besson, and others, to be worked 

 by a spiral spring, which being drawn to the bottom 

 of a cylindrical vessel, water may be poured in above 

 it, and being then tightly covered, with a lid having 

 either an open jet or a tap in the centre, on releasing the 

 spiral spring, the false bottom rising, and pressing the 

 liquid, causes it to escape in a jet d eau, gradually 

 diminishing as the spring relaxes. The contrivance 

 is elaborately illustrated in the the 18th folio engraving 

 of Besson s &quot; Theatrum Instrumentorum et Machina- 

 rum,&quot; 1578 ; the Marquis, therefore, had only to substi 

 tute steam for the spiral spring. 



26. 



To raife weight as 7 well and as 

 forcibly with the drawing back of 

 the Lever, as with the thrufting it 8 

 forwards ; and by that means to lofe 

 no time in motion or ftrength. 

 This I faw in the Arcenal at Venice? 



7 so for as. 8 of it. 9 at Venice in the arsenal. 



[A to and fro Lever.~\ William Bourne offers the 

 following as his 112th Device, &quot;touching the making 

 of engines to thrust from or pull to you with great 

 force or strength.&quot; He says, u And furthermore, you 

 may make an engine to thrust from you or to pull unto 

 you, to lift vp or to presse downe with great force, 

 eyther to goe with wheeles as before is declared, or 

 else to goe with skrewes or to goe with both, as to 

 thrust open huge and strong gates, or else you taking 

 good hold, to pull them open vnto you wards, and will 



