344 TUBULAR BOILER, SUPERHEATING-' STEAM, 



all of these points according to convenience, in combination 

 with the other necessary parts of steam-engines in common use. 

 " These, my essential p.oints, will admit of various modifica- 

 tions as to form and proportions such as must be and are quite 

 familiar to every competent steam-engine manufacturer, and 

 therefore it will be sufficient for the perfect description of my 

 improved steam-engine that I explain some of the modes of 

 forming and combining the essential points of my invention 

 with the other parts of steam-engines in common use. In my 

 most favourite form of engine in which I condense by a current 

 of cold air, the fire-place and flue, the boiler, the condenser, and 

 the air-vessel, are made of six concentric tubes, standing in an 

 upright position. The inner or first tube forms the fire-place 

 and flue, and at the same time the inner side of the boiler. 

 This tube is conical, having its small end upwards. The next 

 or second tube is cylindrical, about 6 inches larger in diameter 

 than the lower end of the first tube, and forms the outside of 

 the boiler, leaving a space all round of about 3 inches at the 

 bottom, and so much more at the top, as the flue is taper for 

 holding water and steam between the two tubes. The third 

 tube is about 2 inches larger in diameter than the second, in 

 order to allow a space of about an inch for powdered charcoal or 

 some other slow conductor of heat. This tube also constitutes 

 the inner side of the air-vessel. The fourth tube is about 

 2 inches larger than the third, and forms the inner side of the 

 condenser. The fifth tube, about 2 inches larger than the fourth, 

 forms the outside of the condenser ; and the sixth tube, about 

 2 inches larger than the fifth, forms the outside of the air-vessel, 

 and at the same time the outside of the whole of the generating 

 and condensing apparatus, consisting of fire-place, flue, boiler, 

 condenser, and air-vesse\. These tubes are made of wrought- 

 iron plates riveted together, and are all cylindrical, except the 

 first, which is conical, the bottom or fire end being the largest. 

 The first or inner tube is closed at bottom, but has an opening 

 on one side near the bottom, through which the fire-bars are 

 introduced, and the ashes and clinkers taken away. To this 

 opening a neck-piece about P> inches long is riveted, having a 

 flange to fit against the inside of the second tube, when the two 



