Some Experiments in Propulsion. 7 



Art. II. — Some Experiments in Propulsion. 

 By S. R. Deverell, Esq. 



[Read 12th April, 1877.] 



The following are particulars of some experiments made at 

 Torbay (England) in February last, by Mr. B. Tower, of 

 Newcastle-on-T^aie, respecting the application of the power 

 represented in the movement of a ship on waves. The 

 experiments were made in the presence of Mr. W. Froude, 

 F.B.S., and Mr. H. Brunei. The vessel in question was a 

 miniature ship of six (6) feet in length, and was lent for the 

 purpose from the Admiralty Works at Torquay. The appa- 

 ratus used was similar in plan to that of a model exhibited 

 at the Exhibition in Melbourne in 1873, with the exception 

 that a strong metallic spring was employed instead of a 

 pneumatic one. The tension on the spring was such that 

 when the vessel was horizontally placed in smooth water 

 the loaded working beams of the machinery were also 

 horizontal. The relative motions of the load were limited 

 to one dimension only — viz., in a plane at right-angles to the 

 plane of the deck. These relative movements were imparted 

 to a ratchet-wheel, causing it to revolve continuously in one 

 direction. The shaft of the ratchet actuated a large wheel 

 and pinion, and the continuous rotation of the pinion was 

 ultimately conveyed to the screw shaft by an indiarubber 

 band accumulator, which stored up the power transmitted 

 to the screw. 



As the vessel was decked, and had only been lent for the 

 trial, the machinery had to be placed above deck, and owing 

 to this it could not be loaded to its full power : a load of 

 only seven pounds being placed on it. This was a serious 

 disadvantage, as, had the machinery been below, a load three 

 times as great would have been placed on it, the power 

 developed being increased in the same proportion. Not- 

 withstanding this, the results completely verified the calcula- 

 tions which had been made respecting the operations of the 

 machinery, the screw on an average making forty (40) 

 revolutions per minute, the vessel attaining a speed of 3J 

 knots against a head , sea and mnd. The maximum effect 

 was observed to take place when the play of the load was 

 isochronous with the period of the waves ; whenever this 



