extent diminished, and though the life of the rail is prolonged, the prolongation is uncertain. The same objections apply to the puddled steel rail, and it is also liable to vary considerably in its hardness and to be at times too brittle for perfect safety. This liability to vary in quality is inseparable from the mode of manufacture as at present practised; and though many very good rails of this kind have been produced, the want of certainty in the manufacturing process seriously diminishes its value.

The introduction however of Bessemer's system has opened out a mode of producing a pure homogeneous hard and tough material, most admirably suited for the manufacture of rails; and though their cost may for a time prevent their being extensively used, there is no doubt that on every railway there are certain places where they would be laid with economy, where the traffic is so constantly severe that ordinary points and crossings have to be renewed on an average four times a year. Once laid of cast steel rails, they would give no

trouble for many years.

In the Bessemer process the pig metal is reduced in a reverberatory furnace, and is then run by a trough into the blowing or converting vessel, in which air is forced through the fluid metal for about 20 minutes, or until the fluid pig is almost entirely decarbonised. A small quantity of melted pig containing a known proportion of carbon is then added, and the charge of converted metal is then transferred to a ladle from which it is poured into ingot moulds, not however by the usual mode of canting the ladle, but by opening a valve in the bottom of the ladle, which allows only the pure metal to run out into the moulds. The ingots are cast of such weight and form as are necessary for the production of each rail. Thus for a 6 yard rail of 84 lbs. per yard, the ingot requires to be 9 inches square and 26 inches long. This ingot is hammered down to 6 inches square and 5 feet long, and then rolled in the ordinary way. It will be evident that the only limit to the length of the rail made in this simple manner is either the weight of the ingot which can be produced or the length of the rolling mill or heating furnace. It is as easy to produce long lengths as short ones; and in this respect the above method has some advantage over piling..

There is no tendency to lamination in this perfectly homogeneous material, and its toughness and ductility are remarkably shown by the specimens exhibited, all of which have been twisted and bent while cold. Its tensile strength is upwards of 40 tons per square inch.

Cast steel rails are not an entire novelty; for several years ago a few were made at Ebbw Vale and were laid at the bridge at the north end of the Derby station, and there they are at the present time perfectly sound and good, whilst the neighbouring iron rails have been many times worn out and replaced. But these rails were made at a great expense from ingots cast in the old or usual method, and the imperfect appliances then existing made it impossible to introduce them commercially. Still the experiment at Ebbw Vale has clearly proved the far greater power of resisting wear and tear possessed by the steel rails; and now the method of producing ingots by the Bessemer process enables rails to be produced which bid fair to become in truth a really "permanent way."

Armour Plates.-In the further portion of the present paper, on the manufacture of Armour Plates, the writer's principal object is to elicit discussion upon this important subject; and as but a very short time has elapsed since the rival powers of the penetration of shot and the resistance of plates have been so seriously and energetically tested, it is necessary to speak with diffidence upon a matter which on all hands is allowed to be as yet imperfectly determined. No limit has yet been assigned to the magnitude of future artillery, nor has any degree of impenetrability of iron plates been declared unattainable. The manufacturer's business is simply to make the best and strongest armour which at the present time is wanted, and leave future possible requirements to be dealt with when the benefits of experience have been obtained. It does not come within the province of this paper to discuss the several questions involved in determining the best form of vessel to carry the weight of armour, nor to settle the resisting power of iron as compared with wood. The iron-maker's problem is how to produce the largest plate of iron of the maximum degree of toughness.

Two methods of producing large masses of wrought iron have been in use: the first by the process of building up under the steam hammer,

and the second by building up under the rolls. Under the steam hammer, the plate is produced by welding together lumps or masses of scrap iron, each mass of scrap being added and welded to the end of the plate, until it reaches the required length. Plates made in this way have been seriously objected to on account of their brittleness; and it is reasonable to suppose that this mode of manufacture is somewhat likely to induce brittleness. There can hardly be any continuity of fibre in a plate forged from masses of scrap iron, perhaps of different qualities, each at different heats; the nature of the weld and its form, and the repeated cooling and re-heating of the plate, are also adverse to its possessing great toughness. The rolled plates have been found more uniform in quality and of greater toughness than the hammered; and though the difficulties in their manufacture are grave, there is no departure from the ordinary practice followed in making large plates for other purposes. The difficulties which do exist are chiefly due to the immense weight and size and the intolerable heat of which must be dealt with while at a welding temperature. The general size of the armour plates required for the plated frigates is from 15 to 18 feet long, from 2 feet 6 inches to 3 feet 10 inches wide, and 4 inches thick. The weight therefore of the finished plate ranges from 60 to 110 cwts.; and in the unfinished state it comes from the rolls at 80 to 140 cwts. From 3 to 4 inches is cut off the sides, and 10 or 12 inches from each end; and in this item of waste the hammering process has an advantage over the rolling.

the mass,

The mode of manufacture of a 5 ton plate is as follows. Bars of iron are rolled 12 inches broad by 1 inch thick, and are sheared to 30 inches long. Five of these bars are piled and rolled down to a rough slab. Five other bars are rolled down to another rough slab, and these two slabs are then welded and rolled down to a plate of 1 inch thick, which is sheared to 4 feet square. Four plates like this are then piled and rolled down to one plate of 8 feet by 4 feet and 2 inches thick; and lastly, four of these are piled and rolled to form the final entire plate. There are thus welded up together 160 thicknesses of plate, each of which was originally 1 inch thick, to form the finished 4 inches, making a reduction of 35 times in thickness; and in this operation from 3500 to 4000 square feet of surface have to be

perfectly welded by the process of rolling. It is not surprising that even with the greatest care blisters and imperfect welds should exist and render the plate defective; this is the chief difficulty to be overcome, and a very serious one it is; and as the magnitude and weight of the plate increase so does also the liability to failure.

The final operation of welding the four plates of 8 feet by 4 feet by 24 inches is a very critical matter. To bring a pile of four plates of these dimensions up to a perfect welding heat all through the mass, without burning the edges and ends of the plates most exposed to the fire; to drag this pile out of the furnace, convey it to the rolls, and force it between them, in so short a time as to avoid its losing the welding heat, is a matter of greater difficulty than those unacquainted with the work would imagine. The intensity of the heat thrown off is almost unendurable, and the loss of a few moments in the conveyance of the pile from the furnace to the rolls is fatal to the success of the operation.

Figs. 1, 2, and 3, Plates 27, 28, and 29, of the armour plate mill at the writer's works.

show the arrangement

Fig. 1, Plate 27, is

a general plan of that portion of the works: Fig. 2, Plate 28, is an enlarged plan of the heating furnace and rolls and Fig. 3, Plate 29, an elevation of the furnace and rolls.

The pile of four plates A, Figs. 2 and 3, Plates 28 and 29, which united form the finished plate, is heated in a special furnace B, and is drawn out by a liberating chain attached to the roll on to an iron carriage C which conveys the pile to the rolls D. The carriage C travels upon a line of rails let into the ground; and close in front of the roll frame is a small incline E upon the railway, which lifts up the front of the carriage at the moment of its arrival at the rolls, and enables it to deliver the pile upon the fore-plate. As the plate passes through the rolls it is received on the other side upon a roller frame F, which is set at a considerable inclination towards the rolls, so that the tendency of the plate is to return. The rolls are then reversed; and the plate which was pressing against them passes back through, and is received upon the carriage C; and again the operation is repeated until the 10 inches thickness is reduced to 4 inches.

T

The plate is then lifted off the carriage C by the crane G, and deposited upon a massive cast iron straightening bed H, and an iron cylinder I weighing 9 tons is rolled over it to and fro, being pinched along by hand levers, until the curvature which the plate has acquired in the rolling is entirely removed. As soon as the plate is sufficiently cool, it is lifted off the straightening bed H by another crane K, Fig. 1, Plate 27, and laid upon the planing machine L, where the final operation of planing its sides and ends is completed.

Mr. BROWN exhibited specimens of the steel rails, fractured to show the quality of the metal; and pieces of the rails that had been bent double while cold without fracture: also a piece of 75 lbs. double headed rail which had been drawn down hot into a bar 1 inch square and then twisted cold without showing any tendency to cracking or splitting.

The CHAIRMAN enquired where the steel rails were laid, and how long they had been down, and what appeared to be their durability.

Mr. BROWN said there were not many rails laid down at present in this country, and they had been used hitherto mainly on the continent; the longest had been down about six or seven months at the new Pimlico Railway Station in London, and had proved very satisfactory: they were answering admirably, and were in as good condition now as when laid down; and a set of steel points and crossings had also been in constant use for seven months at the same station. There were also some of the steel rails more recently laid on the Caledonian, Lancashire and Yorkshire, London and North Western, and Rhymney Railways, but these had not yet been down long enough to afford any results as to their durability.

The CHAIRMAN asked whether there had been any fractures of the rails in working, and what was the cost of them.