IN the bottom of the boat, on the Kelson, there is a trunk, the after end of which is open, and terminates at the stern post ; the other end is closed, and the whole trunk, according to its dimensions, occupies about three fourth parts of the length of the boat. On the closed end of the trunk stands a cylinder two and a half feet long, from this cylinder, there is a communication by a tube to the river or water under the boat, on the top of this tube and within the cylinder there is an-aive to admit the water from the river into the cylinder, and it likewise prevents it from returning again the same way. There is another communication which lets water pass freely from the cylinder to the trunk, through which it is discharged by the stern ; on the top of this cylinder there stands another of the same length, which is fixed to the under one Uy screws; in each of these cylinders there is a piston which moves up and down with very little friction ; these pistons are connected together by a smooth bolt, passing through the bottom of the upper cylinder ; the lower cylinder acts as a pump, which draws water from the river through the tube and valve, before described. The upper cyhnder acts as a steamengine, and receives its steam from a boiler under its piston, which is then carried up to the top of the cylinder by the steam (at the same time, the piston of the lower cyUnder is brought up to its top, from its connection M-ith the upper piston, by the aforesaid bolt,) they then shut the communication from the boiler, and open another to discharge the steam for condensation j by this means the atmosphere acts upon the piston of the upper