30 TEAR-BOOK OP FACTS. 



Rodger's and Trotman's Anchors, with those made on Martin's 

 principle. The experiments were made on the sands, by the south 

 side of the Tyne, near to the works of Messrs. Hawks, Crawshay, 

 and Sons, the manufacturers of Martin's anchors. One of Rodger's 

 anchor's, one of Trotman's, and one of Martin's were chosen to be 

 tested. They were placed upon level ground, and in pairs, drawn 

 together by means of a tackle composed of two triple blocks and 

 a chain paul, having a winch with fly-wheels upon each end, and 

 set in motion by men. The relative weights of the anchors were as 

 follows: — Rodger's, anchor, 5;',- cwt.; stock, l;'j cwt. ; anchor and stock, 

 7.1 cwt. Trotman's, anchor, 4] cwt. (nearly) ; stock, f cwt. ; anchor 

 and stock, 5A cwt. Martin's, anchor complete, 5 J cwt. The relative 

 lengths of the shank, stock, and arms of Rodger's and Trotman's 

 were nearly the same ; Martin's differing from them owing to the 

 nature of its construction. The first trial was made with Rodger's 

 and Martin's, and the result in this case was, that while Rodger's 

 anchor dragged 55 feet nearly before taking a good hold, Martin's 

 only came home about 12 feet, and then got quite immovable. When 

 the anchors were reversed, a similar effect was produced, and it was 

 only when Rodger's was loaded with a weight of 4 cwt. that it gave 

 results equal to Martin's. The next trials were made with the same 

 anchor of Martin's in comparison with the above-mentioned one of 

 Trotman's ; in this case Trotman's dragged (J2 feet before it held firmly, 

 while Martin's ceased moving at 7 feet; the same results were obtained 

 by reversing the positionsjof the anchors, and even when considerably 

 loaded, both Rodger's and Trotman's anchor continued to cut through 

 the ground, while Martin's remained quite fixed. So completely was 

 the superiority of Martin's anchor proved by these experiments, that 

 immediately after the trial a certificate was presented, signed by the 

 Master and Brethren of the Board, expressing their most complete 

 satisfaction at the results, and declaring their conviction that 

 Martin's patent anchor was vastly superior to any other in use, both 

 in a national and commercial point of view, and that by its general 

 adoption many lives as well as much valuable property would be 

 preserved from destruction. — The Engineer. 



IRON-CASED SHIPS OF WAT.. 



Mr. JosEFiiWumvoRTH, in a letter to the Tima,Ba,ju: — "There is 



no doubt but that ships may be built which are proof against ordinary 



shot, but my experience leads me to believe that t, tion of 



armour-plates is a question of firing against them a projectile under 



roper combined conditions; these are, that it shall be of the 



proper shape, material, and weight) and Have the requisite w ' 



A fiat-fronted projeotile of properly hardened material, and weighing 



less than an ounce, fired from one of my ordinary rifles, will pene- 

 trate wrought- iron plates C-lOths of an inch tiiiek. Again, plates 4 

 thick are penetrated by the mi lb. projectiles, and 1 have no 

 doubt but that 6-inch plates would be penetrated by heavier pro- 

 jectiles, with a more powerful gun. Increased thickness ol plate, 

 then, is to be overcome by increased power of guu ; and the question. 



