Propeller for Steam Ships. 5 



Description of the Propeller (see plate).— The propeller 

 consists of a shaft, A, with two arms, B, C, and two floats, 

 D, E. The shaft is hollow, and, in the model, consists of an 

 iron tube of one inch diameter, and five feet long ; the two 

 arms are fixed on the shaft near its extremity, in the form of 

 a semicircle, with the concavity outwards, and they terminate 

 three inches from the shaft, in a hinge point, to which the 

 floats are attached. The floats consist of thin sheet iron, and 

 are of an oblong shape, being 9 inches in length, and 12 

 inches in breadth. They are rounded or semicircular at 

 the extreme end, and more rectangular at the opposite end, 

 where they are hinged to the arms. From the hinge to the 

 shaft there is a narrow projecting part, which rests on the 

 shoulder F when the propeller is in action. From the con- 

 struction of the joint the floats have an extensive motion, 

 permitting them to feather either for forward or backward 

 motion. The shoulder F is of brass, and being double, pre- 

 sents the form of a cross, and is fitted into the extremity of the 

 shaft by a screw, at the same time this brass shoulder is 

 connected to a smaller iron tube inside the shaft. This ar- 

 rangement is for the purpose of turning the brass shoulder, 

 and°this is effected by means of the handle G, at the opposite 

 end of the shaft, where there is also a stop, by which its 

 motion is limited to a quarter of a circle. The shoulder in 

 one position secures the floats for forward motion, and in the 

 other position for backward motion. In forward motion, if 

 the shoulder is turned while the floats are resting on it, their ^ 

 action becomes reversed in the return stroke, and in the 

 same way in backward motion, if the shoulder is turned while 

 the floats are resting on it, the backward motion becomes 

 changed to forward motion. 



To obtain uniformity of motion it will, under any circum- 

 stances, be necessary to have two propellers. 



In large vessels it is proposed that the shafts of the pro- 

 pellers should work in the dead wood in front of the stern- 

 post, and that the dead wood should be extended to the 

 length of the stroke of the propellers, two horizontal spaces, 

 E and F, being prepared for their reception, and provided 

 with guides above and below, the floats, on either side of the 

 dead wood, working free of the ship. 



The shafts being thus secured, it is considered that the pro- 

 pellers will be very little liable to be affected by heavy seas, 

 probably much less than the paddles or screw. 



The propellers may be worked by two levers, and either 

 one or two cylinders, as represented in Plate II. 



