this powerful mangle, and the act of mastication begins. As towel after towel disappears, the rubber is worked into a huge bolster, which is masticated over and over again, until it assumes the form of sticky pulp—“bladder pop," in fact, on a large scale. The bolster is now taken from the machine, and placed in a hydraulic press, one foot wide, nine inches deep, and six feet long. Here it remains for two days under a pressure of fifty tons, and comes out a solid block of homogeneous india-rubber, big enough for a Titanic drawing-master. It has now to be cut into sheets. This is done by placing it in a machine fitted with a cutter, which cuts with a quick lateral or saw-like motion. The block is pushed forward against this cutter, and the thickness of the sheet can be regulated to the hundred-andtwentieth of an inch: indeed, sheets of that tenuity are sometimes made. It is a pretty sight to watch the thin film of rubber being detached in this way with an unerring accuracy.

The most important application of india-rubber in this form is its use as an insulator for telegraphic purposes. Hitherto, gutta-percha has been almost universally employed for deep-sea cables especially; but there can be little doubt that india-rubber is a far more durable material, and it is slowly coming into use, notwithstanding the opposition of the manufacturers who have embarked large capital in the collection and working of gutta-percha. It is one of the most interesting sights in the manufactory to see the machinery envelop the telegraphic wires with its nonconducting rubber sheathing. This is done by winding round them spirally thin bands of rubber by machinery driven by steam-power. Thirty or forty spindles for this purpose are seen revolving in a large room, and hundreds of miles of wire are thus covered in the course of the week. The covered wire is subjected afterwards to heat, which fuses the laps of the covering riband of rubber together, and thus makes it impermeable to the entrance of water, and effectually prevents the escape of electricity.

The process of manufacturing soft india-rubber is more elaborate. What is termed spread sheet india-rubber, or that kind of which waterproof garments are manufactured, is made by masticating, and mixing sulphur in the proportion of two ounces to a pound of the rubber, and then dissolving it to the consistency of dough by the admixture of naphtha.

When in this soft state it is passed through finely adjusted rollers and spread out into thin sheets; these, as they emerge from the rollers or rolling-pins-for the rubber is spread out like so much dough-are passed over a steam chest, which drives off the naphtha, and dries, to a certain extent, the material. In some cases, the film is rolled on to a cotton fabric and adheres to it, film after film being added until it is built up to the required substance: the object of this building up being to prevent the possibility of air-holes occurring, which would be fatal to a waterproof or airproof material. When it is not necessary for the indiarubber to be lined with cloth, the roller of that material on to which it is wound is sized; consequently no adhesion takes place between the two materials, and the rubber is easily peeled off. The process of vulcanization that gives such extraordinary resiliency to the material, which we are so familiar with in the form of india-rubber bands, springs, etc., is accomplished by the application of heat. The sulphur having already been worked into the material, and thoroughly incorporated with it, the articles made of this hard compound are carefully packed in sand so as not to touch one another, and then are run into steam chests, where they remain from two to six hours, according to thickness, at a heat varying from 200 to 300 degrees. This application of heat turns the soft doughy substance into the famous elastic material which, under the name of vulcanized india-rubber, is even invading the province of steel in the manufacture of springs. What is the nature of the chemical change which takes place when this final increment of heat is applied is entirely unknown, and the discovery itself was one of those fortunate accidents which have so often produced noble fruit. The peculiarity of the elasticity produced by vulcanization is, that its power never seems to be worn out. The bow must be unbent, if its force is to be husbanded; but an india-rubber band may be kept stretched to its utmost limit for years, and it will still retain its wonderful resiliency.

But we have yet to describe another process-that of manufacturing hard india-rubber. To Goodyear, the American, the merit of this great discovery is due; for great we must call it, inasmuch as it has introduced into the arts and sciences a material somewhat similar to horn, but which possesses qualities far surpassing that natural pro

duct, and which can be made in any quantities and in any sizes.

In this new material a very large amount of sulphur is used to produce mere vulcanization two ounces to the pound of rubber is sufficient; but to make hard india-rubber, or ebonite, as the Messrs. Silver term their preparation of it, as much as two of sulphur to one of rubber is used. The application of great heat, say 300 degrees, transforms the indiarubber thus treated into a material more resembling ebony in appearance than anything else—a dense black substance, which takes a high polish, is very light, and to some slight extent elastic. The uses to which hard india-rubber is put can scarcely be enumerated. In many articles it is entirely displacing horn and tortoise-shell. Hundreds of tons, for instance, are sold to the comb-makers; for paper-knives, handles of all kinds, bracelets most closely imitating jetbut with this advantage over that material, that it will not break by falling on the floor-cups and troughs of all kinds, and especially those for the use of photographers, as neither acids nor metals have action upon it; in short, we scarcely know to what this beautiful hard substance is inapplicable, so multifarious are the uses to which it has already been applied. It is greatly used as an insulator in telegraphy, in consequence of its non-conducting quality; and moulded. into forms before being baked, it takes the place of many articles formerly made of gutta-percha, to which material it is infinitely preferable, as it is neither affected by heat nor cold.

One of the latest applications of the material brought out by Messrs. Silver is their "patent anti-recoil heelplate," for neutralizing the recoil in rifles and other guns. It is well known that the Martini-Henry rifle, adopted by the Government for the army, is a terrible "kicker,” often inflicting more or less serious damage on the firer, and, of course, materially interfering with the aim in the field.

The little community of Silvertown is, so to speak, selfcontained. Situated, as it is, far away from the town, on the Essex shore of the Thames, the proprietors had, as it were, to found a little colony. When the factory was built, there were no houses near, and no market, consequently the Messrs. Silver had to provide for the wants of their workpeople, and they certainly have done so with a care worthy of all praise. The rows of cottages in which many of their

workpeople are housed, contrast very favourably with the squalid habitations one passes on the railway in going to the factory. Then there is a store in which bacon, flour, and many other necessaries of life are obtainable at cost price, and a public-house in which the beer is pure. The Messrs. Silver found it was incumbent upon them to build a public-house, otherwise it would have been done for them by independent parties, and the consequence would have been that a very efficient means of administering to the comfort of the workpeople, and at the same time of controlling excess, would have passed out of their hands.

The great charge brought against the manufacturers, as a class, used to be that they were utterly careless with respect to their "hands," and that they looked upon them merely as machines or rather less than machines for when their day's task was done, they washed their hands of them, and cared not what became of them; a state of things which placed the free Englishman, as regards physical comfort, in a less favourable position than the negroes, whose bodily wants their masters have always had the good policy to attend to. In thus making themselves responsible to a certain extent for the domestic comfort of their workpeople, the employers are doing service to the community at large; for it is to the exertions of individual manufacturers that society must look for the accomplishment of that all-important task, the elevation of the social status of the workman. The example of little communities such as Silvertown is beginning to tell upon that mass of squalor which once seemed to be so hopeless in its immensity. It is becoming a habit of large manufacturing companies, we are happy to see, to look upon their workmen as human beings, to be cared for, rather than as machines, to be used up; and the formation of the two little colonies of engineers at Wolverton and Swindon has been followed on a smaller scale by thousands of private employers throughout the country, who have found out that their own interests are concerned in concerning themselves with the happiness of those in their employ. The Messrs. Silver may justly pride themselves in belonging to the noble brotherhood of scientific men which is doing good service to the commonwealth.

In addition to this social benefit, they have contributed a national benefaction in the promotion of a volunteer corps in the locality, which has been declared second to none in

efficiency, organized and commanded by one of the firm, who has devoted to it his utmost vigilance for many years, eliciting the thorough approval of the authorities.

"Silvertown," however, became too "elastic" for the proprietors, and the concern was, about twelve years ago, converted into the "India-Rubber, Gutta-Percha, and Telegraph Works Company," under which designation it has been developed at least one hundred-fold in all its bearings.