Hydraulics,

potion for an Hogshead, Hence 52 fs Strokes, each; ur^ nc ^ es ’ W1 ^ raise one Hogshead. And this, 1 _ ieeight be not greater than 10 Feet to which the a-ter is raised, may be done by an able Man m one Mt -^ute y working so as to be able to hold it all Day; ashas been found by Experience. And therefore this is|, 0 he looked upon as the greatest Effect, which Per-°ns can expect from any Hydraulic Engine, to raiseater of any Kind whatsoever, unless he can inventt'^phing more compleat and perfect in this Kind, thane Pump we have now been describing,

58. Another excellent Pump, of the listing Sort, isne Invention of Messrs. Gosset and de la Demllt , and letpp ln the Kino- of France’s Garden at Paris. Thist^mp has this Peculiarity, that its Piston works without7 nct 'on. The Form and Structure thereof is as fol-'oivs: ABC DEFGHIKL is a fort of Box m-ciosing the Piston. This Box consists of two Parts,upp er A B C I K L, and the under orse DEFGH,* h «h shut upon each other, The Piston within is ab>3nd ‘S a circular Piece of Wood, about the Curcumfe-r f nce of which is nail’d a Piece of well seasoned Lea-fe r , of a circular Form, and so wide, that when theI>Hvn is placed at the Bottom of the Box, the Leather£ay li e o ; er the Sides thereof at D H all around ; thej.'fton an d Leather thus placed on the upper Part, isr° rce d down upon the Leather, and then both Parts-rew’d very fast together. The Manner of which isy c 'y ea sy to apprehend from the Figure, where * gfdh k! s Leather goino- from the Piston through the Join-tur eoftheBol. °

59- Upon the upper Part of the Piston is fixed a cir-y U ar (or any figured) Piece of Iron or Wood, denotedde A in the Top of which, at <?, is fixed the Rodthe Pist 0 n Q^C, by which the Piston is drawn upowards the upper Part of the Cavity I », and fromlence forced down again in working the Pump. Nowp . Diameter of the Piston is less than that of thelt: * s P^iu that in, its Motion up and down, nonction can happen, as there are no Parts for it to ruba gainst 5 which is occasioned by the Contrivance of sus-pending it on the Leather.

■Vow. II.

F

60. In