586 
THE DEVELOPMENT OF ARMOUR. 
Nickel. 
On July 21st, 1898, Brown’s and on Sept, 29th, 1898, Cammeirs 
11|£ Krupp plates gave excellent results 1 and it may now be hoped 
that the Sheffield firms have overcome most of their difficulties. 
As said already, Nickel had come into use in Sheffield before the 
adoption of the Krupp process, any difficulties attendant on its use 
being more than compensated by the toughness it imparts when used 
skilfully. In the United States a 12-in. Krupp plate made by Carnegie 
was tested on Sept, 22nd, 1898, at Tndianhead. It defeated an attack 
nearly agreeing with that applied to our Sheffield plates, but was per¬ 
forated by a 12-in. 850 lb. shot with 2,022 f.s. velocity. One 
objection to the use of Nickel was the difficulty of making holes in the 
hardened face of a Nickel steel plate, even with the application of the 
electric arc drill. In Sheffield, even before Nickel was adopted, holes 
were generally drilled before the final hardening of the face, such holes 
being filled with plugs during the last process. It is, however, 
desirable to secure the power of drilling and tapping holes in the face 
of an armour plate, even after it is fixed on a ships side for the attach¬ 
ment of swivels, ladders, etc. In the United States the difficulty of 
drilling holes in a hardened Nickel steel face has been overcome by a 
process projected by the Thomson Electric Welding Company. In 
this two copper contacts are applied at the spot required to be softened, 
and an electric current of large volume is sent through the portion of 
plate lying between them which is brought to a dull red heat. With¬ 
out describing here the special apparatus employed, it may be said 
that it is such as can be applied out of doors to the vertical armour of 
a ship and safely handled. If, however, the current ceases abruptly, 
the mass of metal surrounding the heated spot at once chills it hard, 
consequently in the case of an isolated spot for a single hole, the 
current must be gradually decreased. The neatest application of the 
process is to the case of cutting a gun port in a shield. It may happen 
that the form and mass of the plate in which the port is required is 
such that if the port is made before hardening, the shield during that 
process cracks in two, consequently it has been found best to cut the 
port after hardening. The outline of the port to be cut is annealed bv 
causing the copper contacts to travel slowly along it, annealing it by 
the current as they go. By this means, a strip about 2J inches wide 
is softened, which can be operated on as easily as before the 
hardening process. Fig. 29 shows Brown’s forging press. 
The following is a brief description of the hardening of a 9-in. 
Harveyed plate for H.M.S. “ Majestic,” as witnessed by the writer in 
1894 at Brown’s Atlas Works, Sheffield. 
The chilling is practically the final stage in the manufacture of 
Harveyed plates. The plate is heated in a special regenerative gas 
furnace, by which a very easily regulated and uniform heat is obtained. 
The roof of this furnace, weighing twenty tons, is lifted in one piece 
by a crane, and travelled to one side, while a second crane comes over 
the furnace, picks out the plate with four dogs, and places it over the 
1 These results more or less resemble those obtainei by Vickers. The most severe blow defeat¬ 
ed by a thick plate yet recorded, is that delivered on a Krupp 11'8-in. plate on June 6th, 1896, by 
a 12-in. 716 lb shot with a velocity of 2086 f.s., involving a calculated perforation of 27'6 in. iron 
or 2'33 times the thickness of the plate. 
