of the things done by Watt for the engine: he contrived to make the steam push the piston down as well as up. You have observed that in Newcomen's engine steam was used only to push the piston _up_, the atmosphere being relied upon to push it down. Thus we may say that Watt's engine was the first _real steam-engine_, for it was the first that was worked entirely by steam. All engines before it had been worked partly by steam and partly by air. [Illustration: FIG. 10.--WATT'S ENGINE.] Watt's greatest improvement upon the steam-engine is yet to be mentioned. In Newcomen's engine when the cold water was injected into the cylinder it cooled the piston and when steam was let into the cylinder again a part of it, striking the cold piston, was condensed before it had time to do any work and the power of this part of the steam was lost. Watt did not allow the piston to get cold, for he did not inject any cold water into the cylinder. In his engine as soon as the steam did its work it was carried off through the pipe _M_ to the vessel _N_ and there condensed by means of a jet of water which was injected into _N_ (called the _condenser_) by means of a pump _E_ worked by the motion of the beam, thanks again to Humphrey Potter for the idea. This condensation of the steam outside of the cylinder and at a distance from it prevented the piston (and cylinder) from getting cold. In other words, in the Watt engine when steam entered the cylinder it went straight to work pushing the piston. No steam was lost and no power was lost and the cost of running the engine was greatly reduced. It cannot be said that Watt invented the steam-engine--no one can claim that honor--yet he did so much to make it better that he well deserves the epitaph which is inscribed on his monument in Westminster Abbey. This inscription is as follows: NOT TO PERPETUATE A NAME WHICH MUST ENDURE WHILE THE PEACEFUL ARTS FLOURISH BUT TO SHEW THAT MANKIND HAVE LEARNT TO HONOR THOSE WHO BEST DESERVE THEIR GRATITUDE THE KING HIS MINISTERS AND MANY OF THE NOBLES AND COMMONERS OF THE REALM RAISED THIS MONUMENT TO JAMES WATT WHO DIRECTING THE FORCE OF AN ORIGINAL GENIUS EARLY EXERCISED IN PHILOSOPHIC RESEARCH TO THE IMPROVEMENT OF THE STEAM ENGINE ENLARGED THE RESOURCES OF HIS COUNTRY INCREASED THE POWER OF MAN AND ROSE TO AN EMINENT PLACE AMONG THE MOST ILLUSTRIOUS FOLLOWERS OF SCIENCE AND THE REAL BENEFACTORS OF THE WORLD BORN AT GREENOCH MDCCXXXVI DIED AT HEATHFIELD IN STAFFORDSHIRE MDCCCXIX