426 bepokt— 1878. 



first backward revolutions the pressure of water in front on the helm 

 ceases, causing so-called deadwater at the helm ; whereas an increasing 

 pressure of water on the helm from behind results as soon as the backward 

 revolutions of the screw begin to gain in rapidity. The pressure on the 

 rudder from behind, in spite of the vessel's headway, is presumably to be 

 attributed to the fact that the masses of water thrown forward by the 

 screw must immediately be replaced, causing a correspondingly powerful 

 suction, and consequently a current of water acting on the rudder. The 

 conflict between the contending masses of water is clearly visible also on 

 the surface on both sides of the ship (particularly on the right side). 



We beg to hand these results of our observations to the Nautical 

 Association of this town for distribution amongst other masters, and trust 

 that they will likewise communicate the result of their experiments with 

 their respective ships, in order that the data thus collected may be of ser- 

 vice to the seafaring community. 



(Signed) J. Schutz, Master of the s.s. Susanne. 



„ P. Wilke, do. s.s. Marietta. 



„ C. Strbeck, do. s.s. Martha. 



N.B. — The altered operation of the screw being in the main to be 

 attributed to the fact that the backward revolutions transmute the 

 pressure of water on the helm coming from in front to a pressure coming 

 from behind, it is, when carrying out this manoeuvre, of the greatest im- 

 portance that the helm should first be turned after the screw has com- 

 menced to revolve backwards. 



From the ' Sloping and Mercantile Gazette.' 



In connexion with the Board of Trade inquiry recently held at South 

 Shields, before Mr. Stipendiary Yorke, into the collision between the 

 Tabor steamer, of Sunderland, and the brig William and Ann, of Seaham, 

 which happened in the River Thames, on January 25 last, some experi- 

 ments have been made on board the Tabor, at the mouth of the Tyne, 

 on the peculiar effects of the rudder and screw when reversed while the 

 ship has headway, to turn the ship's head to starboard of her course. As 

 far as I am aware, the first public intimation of any similar trials 

 having been made appeared in the Report of the British Association for 

 the year 1876. The Report gives an account of certain experiments made 

 on the Clyde by Professor Osborne Reynolds, Sir William Thomson, Mr. 

 James R. Napier, and others. These experiments were undertaken to 

 verify certain trials made upon models by Professor Reynolds, which he 

 had brought under the notice of the Association the previous year at 

 Bristol. An able article on the subject, from the pen of Sir Travers 

 Twiss, appeared in the ' Nautical Magazine,' last year ; so that nautical 

 men should now be aware that they cannot always depend upon the action 

 of the rudder and screw when reversed while the ship has headway. 



Almost all experienced officers of the navy and merchant service are 

 doubtless well acquainted with the manoeuvring of screw vessels under 

 steam, but it is thought that junior officers and others might not have 

 had opportunities of acquiring information of this kind. There is a 

 marked difference in the results observed on the Clyde and those noticed 

 at the mouth of the Tyne, inasmuch as in none of the trials detailed below 



