1276

THEORY AND PRACTICE OF ENGINEERING.

Book II.

tube fixed in brass rims is attached to the boiler, having at the top a brass cock turned bya handle, and at the bottom another for letting off the water in the glass tube, after the levelhas been ascertained.

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The Cylinders , which are placed in front, are attached to the framework of the boiler ;they are surrounded by heated air, as they are within the front chamber, through whichis the escape from the tubes to the passage of the chimney : in order effectually toprevent any water passing off with the steam from the boiler into the cylinders, the steam*pipe is carried up, as has been described, into a hemispherically crowned cylinder, and

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whatever water boils or bubbles up cannot reach the funnel mouth, intended only forthe passage of steam; before the steam is admitted by the regulator to the pipes,which conduct it to the cylinders, it enters a small chamber, which is an admirable con-trivance, and perhaps one of the most important parts of the whole machine. Thesechambers are placed above the cylinders, and w’ithin them is a movable box or slide, which,as its motion is either backwards or forwards, effects a communication with the steam-