THE ROYAL ARTILLERY INSTITUTION. 
207 
5. Mr. Mallet read a paper before the Institution of Civil Engineers in 
1859* on the coefficients of Elasticity and Rupture in massive forgings 
(T e T r ), in which we find much information respecting the metal used in 
his mortars. A sum of £50 had been granted by Lord Panmure in 1856 
towards the expenses of the investigation. The samples tested are described 
as follows 
Class I. 
“Mark 3 H., No. 1.—Wrought-iron, fagotted, forged slabs, drawn out under the 
steam hammer, 11 ins. by 2'5 ins. rough section; prepared for the chase rings of 
mortar No. 1. 
“ Mark 4 H., No. 2.—The same, drawn out under the steam hammer for the 
chase rings of No. 2. 
“Mark 1 R., No. 3.—Wrought-iron, rolled slabs of the same iron as Nos. 1 
and 2, of the same dimensions, and for the same purpose. Mortar No. 1. 
“Mark 2 R., No. 4.—Wrought-iron, rolled slabs, the same in all respects as 
No. 3. Prepared for mortar No. 2. 
“All these irons were prepared at the Thames Iron Works, London. Specimens 
Nos. 1 and 2 were intended for the internal rings, and Nos. 3 and 4 for the 
external rings of mortars 36 ins. in diameter. The slabs were welded into rings 
or hoops of various sizes, from 7 ft. diameter down to 3 ft., reduced to equal 
thicknesses of 2 ins. Eight plies of these hoops, shrunk one upon the other, 
according to a determinate law of tension, constituted the thickness of the chase 
of these mortars.t The object in testing the iron of these hoops was not only to 
obtain absolute measures of the ultimate resistance of the material employed; but 
also to determine whether the same malleable iron afforded a greater resistance to 
forces of tension and compression, when prepared by means of hammering-or by 
means of rolling the dimensions being the same in both cases. . . . 
“Mark 1 0., No. 5.—Eagotted and forged slabs, prepared for exterior reinforce 
hoops, or rings shrunk upon the central core pieces of the chamber of the mortars. 
The iron for these was prepared from puddled balls of the best selected Scotch and 
North Wales pig iron. The rough bars were hammered into slabs, which again 
were piled and welded up into the required size under the hammer. Each slab, 
when complete, was about 5 * 5 ft. square by 1 ft. thick. The test bars were cut 
out parallel with the broad surfaces of the slab.’ 5 
Class II. 
“MarkP 2, No. 6.—Eagotted, forged bars, welded and drawn under the 
steam hammer, and prepared for the purpose of being again fagotted and welded 
into the great masses intended to be used for the Mersey Company’s gun, and for 
the central or core pieces of the chambers of the mortars of 3 6-inch calibre. This 
iron, constituting the integrant material for all the large forgings, has, therefore, 
comparative reference to both Class II. and III. It was piled and prepared in the 
following manner, and was fagotted into rough bars averaging about lOins. by 
* “ Minutes of Proceedings,” Vol. XVIII. p. 296. 
f This is apparently a clerical error. The drawing only shows seven,—J. H. L, 
