ON THE HISTORY OF HYDRAULICS, &c. 279 



Marquis of Worcester professes to have carried the project into full effect, 

 as We are informed by his account of what he called a fire water work, 

 which fts one of his Century of Inventions, first published in 1663,* and 

 which is thus described : " I have taken a piece of a whole cannon, whereof 

 the end was burst, and filled it three quarters full of water, stopping and 

 screwing up the broken end, as also the touch hole ; and making a constant 

 fire under it, within 24 hours it burst, and made a great crack : so that 

 having a way to make my vessels so that they are strengthened by the 

 force within them, and the one to fill after the other, I have seen the water 

 run l&e a constant fountain stream forty foot high. One vessel of water, 

 rarefied by fire, driveth up forty of cold water : and a man that tends the 

 work is but to turn two cocks, that one vessel of water being consumed, 

 another begins to force and refill with cold water, and so successively, the 

 fire being tended and kept constant, which the self same person may like- 

 wise abundantly perform in the interim between the necessity of turning 

 the said cocks." The machine was, however, not at that time prac- 

 tically introduced, and it was soon forgotten ; Savery's engines were 

 constructed in a manner precisely similar, some time before 1700 ; and 

 it is uncertain whether he adopted the Marquis of Worcester's ideas, 

 or reinvented a similar machine. About 1710, the piston and cylinder 

 were invented by Newcomen, and with Beighton's apparatus for turning 

 the cocks by its own motion, the engine remained nearly stationary for 

 many years. 



As early as the year 1667, the pressure of fluids in motion, and the re- 

 sistance opposed by fluids at rest to the motion of solid bodies, were expe- 

 rimentally examined by Huygens, and some other members of the Parisian 

 Academy. Pardies, whose works were published in 1673, attempted to 

 determine, although upon some inaccurate suppositions, the effects of the 

 wind on a ship's sails under different circumstances. His principles were 

 adopted by Renaud, who published a work on the subject in 1689.t Their 

 imperfections were, however, soon after pointed out by Huygens, and by 

 James Bernoulli; and, in 1714, John Bernoulli published an extensive 

 treatise on the manoeuvres of ships, which at last compelled Renaud to 

 submit to so many united authorities. 



It must be confessed that the labours of Newton added fewer improve- 

 ments to the doctrines of hydraulics and pneumatics than to many other 

 departments of science ; yet some praise is undeniably due both to his com- 

 putations and to his experiments relating to these subjects. No person 

 before Newton had theoretically investigated the velocity with which fluids 

 are discharged, and although his first attempt was unsuccessful, and the 

 method which he substituted for it in his second edition is by no means free 

 from objections, yet either of the determinations may be considered in some 

 cases as a convenient approximation ; and the observation of the contraction 

 of a stream passing through a simple orifice, which was then new, serves to 

 reconcile them in some measure with each other. His modes of considering 

 the* resistance of fluids are far from being perfectly just, yet they have led 

 to results which, with proper corrections, are tolerably accurate ; and his 

 * Invention, 68. f Manoeuvres des Vaisseaux. 



