Propeller for Steam Ships. 9 



propulsion, it does not follow that ten per cent, of the steam 

 power is lost, unless there are very heavy engines to be kept 

 in motion. If the floats are not instantly brought into posi- 

 tion at the commencement of the stroke, it is because the 

 steam cannot instantly re-enter the cylinder with sufficient 

 rapidity to exert its full power on the piston, and if the power 

 is not exerted it cannot be said to be lost. 



A propeller on a new principle must necessarily require 

 important modifications in the construction both of ships and 

 machinery, and if this new propeller should be found to 

 possess any advantages over the paddle wheels and screw, it 

 ought not to be objected that its adoption would render such 

 modifications necessary. 



The principal alterations" required would be a greater 

 length in the dead wood under the stern, with finer lines in 

 the run, and a greater length of cylinder, with increased speed 

 of piston. A stroke of piston of eight, ten, or twelve feet, 

 with a corresponding increase in the velocity of the piston, 

 would suffice for all purposes of speed. 



Great length and fine lines have added greatly to the speed 

 of our modern clippers, and in the new American steam-ship 

 C. Vanderbilt, the cylinders are ninety inches in diameter, 

 and the stroke of the piston is twelve feet ; while the leviathan 

 steam-ship now building at Blackwall will have four cylinders 

 six feet in diameter and eighteen feet long. 



It may be objected to this propeller that reciprocating 

 motion with long levers is not suited for marine engines. 



. All propulsion is effected by means of levers. The floats 

 of the paddle wheels are connected to the shaft by means of 

 levers, and the blades of the screw are equally to be regarded 

 as levers, the only difference being that these levers have a 

 continuous circular motion imparted to them by the crank, 

 and that they act in the water, whereas I propose to impart 

 a reciprocating motion to the propeller by means of levers 

 acting within the ship. 



A single lever of great length, with a reciprocating motion 

 of great velocity, would not act securely or steadily in a 

 rough sea, but if the lever is composed of two separate 

 parallel pieces, three feet apart, and firmly connected together 

 by cross heads at both ends, it will move as securely and 

 steadily on its fulcrum or shaft as the paddle wheels on their 

 shaft, and if the velocity of the piston can be increased to 

 800 or 1,200 feet per minute, for all ordinary purposes the 



