68 EEPOiiT — 1876. 



original direction, i. e. iu the opposite way to that in which she would have 

 turned had the screw been kept on ahead. 



With the helm to starboard, at the end of 10 seconds she had turned 

 through 6° to port, and in 14 seconds more, when she had nearly lost way, 

 she had come back 14° to starboard or S° to starboard of her original direc- 

 tion ; that is, as before, in the opposite way to that in which she would have 

 turned had the screw been kept on ahead. 



With this ship, therefore, althougli the reversing of the screw did not at 

 once reverse the action of the rudder, it greatly reduced its effect, and 

 reversed it in time for the ship to have turned S° out of her course before she 

 had come to rest — that is, 8° out of the direction iu which she headed on 

 the reversal of her screw ; and considering that, during the 25 seconds in which 

 she was stopping, had her screw been kept on ahead she Avould have turned 

 through some 50°, the effect of reversing the engines was to bring the ship 

 some 58° out of the direction she might have occupied. 



Experiments with the Hopper Barge, No. 12, belonging to the Clyde 

 Navigation Trust, Captain J. Barrie, on June 7, off lulcreggan, Rosneath. 



These experiments were conducted in a similar manner to those on the 

 ' Valetta,' the same members of the Committee taking part in them. 



The barge when loaded carries 400 tons of mud, is 140 feet long, was 

 drawing during the first set of experiments 11' 6" aft and 9' 6" forward, and 

 when light, during the second set, 8' 2" aft or 4 ft. forward. The top of the 

 propeller is 8' 6" from the bottom of the keel. The screw, which is right- 

 handed, has three blades, and is 8 feet in diameter and 16 feet pitch. 



The first set of experiments were made with the barge head to windward, 

 the wind being of much the same force as on the previous daj'. The mud 

 was then discharged, and the barge put before the wind, and the experiments 

 repeated. 



When loaded and going to windward with the helm amidships, the barge 

 sheered first to port and then to starboard. This was apparently owing to 

 the screw churning the water intermittently ; when the wake was apparently 

 clear the boat turned to starboard, and when the screw was churning air 

 into the water she turned to port. 



When the screw was reversed with full way on, and afterwards the helm 

 put hard over either to port or starboard, the action of the rudder was 

 always reversed, and was very decided. It required 1 minute for the screw 

 to bring the boat to rest, and during that time she turned from 35° to 60° ; 

 moving slowly at first, aud more rapidly as her speed diminished. 



The reverse action of the rudder Avas therefore much more decided than iu 

 the case of the ' Valetta,' which was accounted for by the fact that the screw 

 was reversed to full speed at once, the engineer being an old locomotive 

 engine-driver accustomed to reverse suddcnlj', besides which the boat being 

 much heavier allowed more time for the operation. 



When the boat was going full speed astern, the screw reversed to full speed 

 ahead, the action of the rudder was the same in direction as if she had been 

 going ahead, but it was very slow. 



When the bai-gc.was steaming full speed ahead with the rudder hard over, 

 she turned at the rate of 1° in 1 second. 



With this vessel, therefore, the effect of reversing the screw wof. to cause 

 her to turn through more than 30° from the direction in which she 

 headed when the reverse action set in ; and considering that in the same 

 time she would have turned through 00° in the opposite direction had the 



