588 
THE DEVELOPMENT OF ARMOUR. 
completed the then shape of the plate, which may have slightly 
changed during heating and handling, is known, and the best method 
of applying the water decided upon. The water is then immediately 
turned on, and issues from thousands of small orifices with great 
pressure upon both the upper and lower surfaces of the plate, cooling 
them almost instantaneously. The application of the water is con¬ 
tinued in the case of 9-in. plates for from thirty-five to forty minutes, 
and the plate is then usually from J in. to \ in. more convex on the 
face than required by the finished moulds. This convexity is purposely 
aimed at, because it can easily be remedied by pressure while the 
plate is cold, whereas an error in the concave direction could not be 
rectified without going through the whole chilling process again. 
Absolute accuracy of form from the chilling operation it is practically 
impossible to secure. After the chilling is finished, the plate is tested 
with large hardened cast steel punches, struck with a sledge hammer, 
which must be fractured against the hard surface without making an 
appreciable indent. All holes in the hard surface required for attach¬ 
ments will have been made previous to the chilling, but the final 
trimming of the edges to exact shape has to be carried out subsequent¬ 
ly. This is accomplished on a planing machine as far as regards the 
soft portions of the edges, but as the planing tool comes up the edge 
to within about three-quarters of an inch of the hard surface, the 
material becomes too hard to be cut with a steel tool. The projecting 
rib thus left is removed by grinding, either on a large grindstone, or 
an emery wheel used as a planing tool. Finally, the bolt holes in the 
back of the plate by which it is attached to the ship are drilled and 
tapped, and the plates are erected in their proper relative position, 
and any slight deviation from exactness of fit is further corrected by 
subsequent grinding. 
Development op Armour on Ships prom 1893 to 1898. 
Two things have specially influenced the shape that ship's armour 
hS/faced ^ as ^ a ^ en during the last few years, namely the development of quick- 
armour! h re and improvement in the quality of the armour itself. Some of the 
elements which constitute quick-fire are now applied to guns of large 
calibre and it is difficult to draw the line where a piece ceases to 
deserve to be called a Q.F. gun; the class of ordnance, however, that 
has influenced the distribution of armour on ships, and indeed affected 
the whole plan and structure of the vessel is the class of gun which 
can be conveniently mounted and worked behind medium armour 
constituting what is termed the ships secondary armament. In British 
ships 6-inch Q.F. guns generally fulfil this function and in foreign 
vessels pieces of 15 or 36 c.m. are often employed, occasionally 8-in. 
and even larger pieces, though the 4‘7-in. gun is much used in British 
cruisers and still lighter pieces in many foreign ships. 1 This 
armament is generally protected by from three to six inches 
of steel armour and it constitutes a means of attack on which 
probably naval officers would principally depend. A projectile, 
1 The writer has repeatedly dwelt on the insignificant power of the 4-in. Q.F. gun armament of 
the U.S, armoured cruiser New York , 
