286 REPORT — 1861. 



Let t be the thickness of the plate in inches, w the weight of the shot 

 in Vas.,v the velocity of the shot at the moment of impact in feet per second, 

 r the semidiameter of the shot ; then, from the experiments at Shoeburyness, 





■ I,, mt.i, jiuiu iiic cApenuiems at onoeouryness, i 



^"^V 337494.0 7- ^^'^ \ 



w 3374940 <" ._ . 



T V 



From the first of these formulas we can find the greatest thickness which 

 will be penetrated by a shot of a given size and at a known velocity. From 

 the second we obtain the coordinate values of the weight and size of the shot 

 necessary to punch a plate of a given thickness. The formulae are only 

 approximate, but they are as accurate as is necessary until the velocity of the 

 shot at impact has been more closely ascertained. It will then be time to 

 determine what modification is necessary to secure an entire agreement with 

 the experimental results. It may be stated, however, that the formulae do 

 not apply to those cases in which brittle plates break up by transverse flexure. 



As respects the fastening of armour-plates, the Committee on Iron have 

 been inundated with schemes from all quarters, but none of them have as 

 yet met the requirements of the case; and until further experiments are tried 

 to equalise the resistance of the fastenings to the resistance of the plates, we 

 are unable to look forward to anything approaching satisfactory results. Bolts 

 and nuts have been tried, and found defective. Strong countersunk rivets 

 have been used, with better success when the plates are attached without 

 wood or any other intervening substance to the skin of the ship ; but even 

 these have been found defective, and are inadmissible when a lining of oak or 

 teak intervenes between the armour-plates and the sides of the ship. An 

 ingenious contrivance has been recommended by Mr. Scott Russell for 

 attaching the armour-plates to the ship, and that is a series of bars, in the 

 form of the letter T^, along the sides of the vessel, between the joints of the 

 armour-plates and the web part a, projecting about an inch and a half beyond 

 the thickness of the plates, heated by a large blowpipe and riveted continu- 

 ously over the edge of each plate. This system of fastening answers well, 

 but can only apply to ships composed entirely of iron, and when the shield- 

 plates rest directly upon the sides of the ship. Extended experiments are 

 yet required to solve this difficult question, and we have every reason to 

 believe they will not be wanting, when other conditions connected with the 

 changes now in progress have been realized. 



Continuation of Report to determine the Effect of Vibratory Action and 

 long-continued Changes of Load upon Wrovght-Iron Girders. By 

 William Faibbaxrn, Esq., LL.D., F.R.S., ^c, President of the 

 Association. 

 At the close of the Oxford Meeting it was announced that the experiments 

 on this important subject were still in progress, and that hopes were enter- 

 tained that they might be completed in time for the Manchester Meeting. 

 Confirmatory of that promise, we have now to submit the results of a still 

 more extended inquiry into the effects of vibratory action on molecular con- 

 struction. It will be in the recollection of the Meeting that, fifteen years 

 ago, experiments were made which led to the designs and construction of 

 the Conway and Britannia Tubular Bridges, on the Chester and Holyhead 



