210 
POPULAR SCIENCE REYIEW. 
and passing through two holt holes. The rail, when subsequently tested, 
was broken by 9 falls of a weight of 300 lbs. from heights increasing from 
5 to 13 ft. The material proved to be of too hard a character to be suitable 
for rails, a fault not unfrequently occurring in the earlier made steel rails. 
Notwithstanding this, the use of steel for rails is making most steady pro- 
gress, and their powers of endurance when once laid appear to be most re- 
markable. In several instances they have outlasted 8, 12, 16, and in one 
instance 22 faces of iron rails without wearing out, a result due partly to 
their greater strength and hardness, and partly to the fact of their greater 
homogeneousness and the absence of those planes of weakness present in all 
welded bars. 
The Monitor Question . — A somewhat warm discussion has arisen as to the 
strength of armour-plating on the American monitors. Mr. Bourne has now 
admitted that he was in error, and that the drawing of the armour-plating 
of the ^Dictator,’ given by Mr. Heed to the Institution of Civil Engineers, 
and published in the last volume of their proceedings, is correct. The 
armour-plating diminishes in thickness, in steps from the water-line to the 
bottom of the armour shelf, so that these vessels do not carry quite so much 
armour as has been commonly supposed. 
War Material . — We may call attention to some very interesting papers 
on war material, contributed by a well-known and accomplished authority 
on artillery, to the pages of the Engineer. They contain an account of the 
most recent improvements in the electro-chronometric instruments for 
measuring the velocities of shot, particularly those of Professor Bashfortli 
and of Captain Schultze \ also some interesting details of the best forms 
of torpedoes, and of the manner of using them ; and a discussion of the 
principle of muzzle-pivoting which was proposed in 1856 by Mr. R. 
Mallet. Muzzle-pivoting consists in the arrangement of the racers and 
slides, and of the gun-carriage, so as to enable all the movements of the 
piece, necessary to aiming at an object, to be effected in the same manner as 
if the gun itself were moved about a point situated at the muzzle, and in 
the axis of the piece. The result is that the gun so mounted can be 
directed and fired through a round aperture or embrasure very little bigger 
than the muzzle of the gun itself. The importance of such an arrangement 
at the present time will be evident. 
Gibraltar Shields . — The Government having constructed some armour- 
plated shields, for Gibraltar and other places, one of which under fire proved 
disastrously weak, have reappointed the Armour-Plate Committee, which 
did such good se:yyice some years since in investigating the application of 
iron for purposes of defence, to undertake further experiments on the same 
subject. 
Steel Ropes. — Messrs. Howell and Co. of Sheffield, have proposed the use 
of laminae or ribbons of steel, which they can roll in any length, in place of 
wire for the ropes of suspension bridges. A specimen of this laminated rope, 
consisting of 48 laminae, 3 in. wide and thick, would, according to their 
statement, require 720 tons to break it, and would not take any permanent 
set with less than 30 tons per sq. inch. It would be easy to place each strip 
over the space to be crossed by the bridge, laying the strips carefully on each 
other, and when the required section is attained, binding them together with 
