The Romance of Industry and Invention. Various

at which each part is shrunk on is the greater as the part is farther removed from the inner tube; the jacket, for example, being shrunk on at less tension than the outer hoops. The inner tube, on receiving the expansive force of the explosion, is prevented by the compression of the jacket from being forced up to its elastic limit; and the jacket in its turn is similarly supported by the outer hoops; and on the cessation of the internal pressure the several parts resume their normal position.

      This system of construction originated in England, and is now in general use. The first steel guns on this principle were those designed by Captain Blakely and Mr. J. Vavasseur, of the London Ordnance Works. At the Exhibition of 1862, a Blakely 8.5-inch gun, on the built-up system, composed wholly of steel, was a feature of interest in the Ordnance section. The plan devised by Sir W. Armstrong, and carried into effect for a series of years at Woolwich and at the Armstrong Works at Elswick, consisted in enclosing a tube of steel within a jacket of wrought iron, formed by coiling a red-hot bar round a mandrel. The jacket was shrunk on with initial tension, and was fortified in a similar manner by outer hoops of the same metal. The want of homogeneity in this gun was, however, a serious defect, and ultimately led to its abolition. The difference in the elastic properties of the two metals caused a separation, after repeated discharges, between the steel tube and its jacket, with the result that the tube cracked from want of support. Both at Woolwich and at Elswick (described on a later page), therefore, the wrought-iron gun has given place to the homogeneous steel built-up gun, which is also the form of construction adopted by the chief powers of Europe and by the United States of America.

      The failure of some of his solid-cast guns led Krupp, about 1865, to the adoption of the built-up principle. With few exceptions, the inner tube of a Krupp gun is forged out of a single ingot, and in every case without any weld. The ingot destined to form the tube has first to undergo a prolonged forging under the steam-hammers, by which the utmost condensation of its particles is effected. It is then rough-bored and turned, and subsequently carefully tempered in oil, whereby its elasticity and tensile strength are much increased. It is afterwards fine-bored and rifled, and its powder-chamber hollowed out. The latter has a somewhat larger diameter than the rest of the bore, this having been found an improvement. The grooves of the rifling are generally shallow, and they widen towards the breech, so that the leaden coat of the projectile is compressed gradually and with the least friction. The jacket and hoops of steel are forged and rolled, without weld, and after being turned and tempered, are heated and shrunk around the tube in their several positions, the greatest strength and thickness being of course given to the breech end, where the force of explosion exerts the utmost strain. The completed gun is mounted on its appropriate carriage, and having been thoroughly proved and tested and fitted with the proper sights, is ready for service. The testing range is at Meppen, where a level plain several miles in extent affords a suitable site for the purpose.

      For many years all guns of the Krupp manufacture have been on the breech-loading system, and he has devoted much time and ingenuity to perfecting the breech arrangements. The subject of recoil has also largely occupied his attention. In the larger Krupp guns the force of recoil is absorbed by two cylinders, filled with glycerine and fitted with pistons perforated at the edges. The pistons are driven by the shock of the recoil against the glycerine, which is forced through the perforations. In England a similar arrangement of cylinders, containing water as the resisting medium, has been found effective; and in America, petroleum is employed for the same purpose. The advantages of the use of glycerine are that in case of a leak it would escape too slowly to lose its effect at once, and it is also more elastic than water, and is less liable to become frozen.

      The resources of Krupp's establishment are equal to the production of guns of any size that can conceivably be required. He has made guns of one hundred and nineteen tons weight. The portentous development of the size and power of modern ordnance is exemplified by these guns and the Armstrong guns of one hundred and eleven tons made at Elswick. Amongst the class of modern cannon, one of the most powerful is Krupp's seventy-one-ton gun. This, like all others of his make, is a breech-loader. Its dimensions are—length, thirty-two feet nine inches; diameter at breech end, five feet six inches; length of bore, twenty-eight feet seven inches; diameter of bore, 15.75 inches; diameter of powder-chamber, 17.32 inches. The internal tube is of two parts, exactly joined; and over this are four cylinders, shrunk on, and a ring round the breech. Its rifling has a uniform twist of one in forty-five. It cannot possibly be fired until the breech is perfectly closed. Its maximum charge is four hundred and eighty-five pounds of powder, and a chilled iron shell of seventeen hundred and eight pounds.

       Krupp's 15.6 Breech-loading Gun (breech open).

      Krupp did much to promote the welfare and comfort of his workpeople. For their accommodation, he erected around Essen nearly four thousand family dwellings, in which more than sixteen thousand persons reside. The dwellings are in suites of three or four comfortable rooms, with good water-arrangements; and attached to each building is a garden, large enough for the children to play in. There are one hundred and fifty dwellings of a better kind for officials in the service of the firm. Boarding-houses have also been built for the use of unmarried labourers, of whom two thousand are thus accommodated. Several churches, Protestant and Catholic, have also been erected, for the use of his workmen and their families. There have likewise been provided two hospitals, bathing establishments, a gymnasium, an unsectarian free school, and six industrial schools—one for adults, two for females. In the case of the industrial schools, the fees are about two shillings monthly, but the poorest are admitted free. A Sick Relief and Pensions Fund has been instituted, and every foreman and workman is obliged to be a member. The entrance fee is half a day's pay, the annual payment being proportioned to the wages of the individual member; but half of each person's contribution is paid by the firm. There are three large surgeries; and skilful physicians and surgeons, one of whom is an oculist, are employed at fixed salaries. For a small additional fee each member can also secure free medical aid for his wife and children. The advantages to members are free medical or surgical treatment in case of need, payment from the fund of funeral expenses at death, pensions to men who have been permanently disabled by injuries while engaged in the works, pensions to widows of members, and temporary support to men who are certified by two of the physicians as unable to work. The highest pension to men is five pounds monthly, the average being about two pounds sixteen shillings monthly. The average pension to widows is about one pound fourteen shillings monthly.

      The firm have made special arrangements with a number of life insurance companies whereby the workmen can, if they choose, insure their lives at low rates. They have formed a Life Insurance Union, and endowed it with a reserve fund of three thousand pounds, from which aid is given to members needing assistance to pay their premiums. An important institution in Essen is the great Central Supply Store, established and owned by the firm, where articles of every description—bread, meat, and other provisions, clothing, furniture, &c.—are sold on a rigidly cash system at cost price. Connected with the Central Store are twenty-seven branch shops, in positions convenient for the workpeople, placing the advantages of the system within the easy reach of all.

      The original name, 'Frederick Krupp,' has been retained through all vicissitudes of fortune as the business title of the firm. The small dwelling in which Alfred Krupp was born is still standing, in the midst of the huge workshops that have grown up around it, and is preserved with the greatest care. At his expense, photographs of it were distributed among his workmen, each copy bearing the following inscription, dated Essen, February 1873: 'Fifty years ago, this primitive dwelling was the abode of my parents. I hope that no one of our labourers may ever know such struggles as have been required for the establishment of these works. Twenty-five years ago that success was still doubtful which has at length—gradually, yet wonderfully—rewarded the exertions, fidelity, and perseverance of the past. May this example encourage others who are in difficulties! May it increase respect for small houses, and sympathy for the larger sorrows they too often contain. The object of labour should be the common weal. If work bring blessing, then is labour prayer. May every one in our community, from the highest to the lowest, thoughtfully and wisely strive to secure and build his prosperity on this principle! When this is done, then will my greatest desire be realised.'

      Germany