"Secondly, the enclosing of the condenser in an air or water vessel, by which the intention of safety from explosion is further provided for, and my engine really rendered what I denominate it, a high-pressure safety engine. "Thirdly, the condensing of the steam in the condenser by means of a current of cold air or cold water forced against the outsides of the condenser. "Fourthly, the returning of the condensed steam from the condenser back again into the boiler, to the end that sediment and concretion in the boiler may be prevented; and, "Fifthly, the blowing of the fire with the air after it has been heated by condensing the steam. "In forming my improved steam-engine I employ several or all of these points according to convenience, in combination with the other necessary parts of steam-engines in common use. "These, my essential points, will admit of various modifications 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-vessel. 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.