190 REPORT — 1864. 



Experiments on the Elasticity of Iron. By James Williams. 



In the engineers' workshop, where straight bars of metal are used for the purpose 

 of testing the work under process of manufacture, it is necessary to keep at least 

 three bars or surfaces of eacli kind for the purpose of testing each other; for it has 

 long been known that a straight edge, got up with all the care and accuracy pos- 

 sible, true to-day will be bent to-morrow ; indeed the very handling of it while in 

 use is quite sufficient to distort it to such a degree that the workman frequently 

 has to put it by awhile until it conies to the natural temperature of the I'oom he 

 works in, the partial heat of the hands alone being sufficient to render it useless 

 for its object. In getting up straight edges and flat sm-faces, if two only are used 

 to test each other, it is all but a certainty that one will be hollow and the other 

 rounding ; but by using three we are enabled to discover this defect. The author 

 showed the flexibility of iron and steel by experiments. 



On Plated Ships and tlieir Armament. By Captain Wheatlet, R.N. 



On Revolving Sails. By Captain Wheatley, R.N. 



On Imjirovements in the Defence of Ships of War. By Captain AVheatlet. 



The author thinks that in future the mode of attacking an iron ship will be to 

 imitate the practice of a breaching battery on shore, where all the guns are directed 

 to a particular spot in the wall to be breached, and to take the ship's water-line 

 as a horizontal line, and the line of any prominent mark, as a mast or funnel, for 

 a perpendicular, and to order all the guns to be directed on the one spot where 

 these two lines meet. He also proposes that screens of oiled south-wester canvas, 

 having a piece of heavy wii-e-rope at the bottom, should be let down immediately 

 the shot has struck, a bag of wood-shavings and a mattress forced into the gap, 

 covered by a plank and shored up from the inner side of the wing. This will only 

 stop the main rush of the water ; a great deal will still flow through the irregular 

 crevices. These he proposes to stop by plastering the canvas to the side vdth 

 liydraulic cement, which is said to become fixed imder water in a quarter of an 

 hour. 



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