tubes or hoops in the recess or cavity, these segmental threads being so arranged that those on the ring will pass endwise between those in the recess, so that the ring may be freely inserted and then turned far enough round to cause the threads thereon to engage with those of the recess. By these means the tubes or hoops are secured firmly and solidly together at the breech end of the gun.

The tubes or hoops of which the gun is composed are preferably made in one piece and are continuously and uniformly tapered throughout their length,

so that the required diminution in the external diameter of the gun from the breech to the muzzle is obtained without shoulders or sudden changes of thickness, which are very prejudicial to the strength of the tubes. The continuous taper of the liner a greatly facilitates its removal and replacement. Moreover, by the employment of the continuously and uniformly tapered

tubes a method of manufacture can be adopted which avoids the necessity for the use of gauges in fitting the various tubes one upon another-that is to say, the builder can turn or otherwise form the outside of one tube and bore out the other tube so that both tubes are continuously tapered at the same angle from end to end and the external diameter of the one is so nearly the same as the internal diameter of the other that the outer tube can be placed very nearly in its ultimate position upon the inner tube without any or with but very slight pressure; then, the remaining distance and the angle being known, it is easy to ascertain the exact pressure to which the tubes will be subjected in forcing the one to its ultimate position upon the other. The liner a may be forced home by applying to it hydraulic or other pressure as great in amount as or greater than the total pressure exerted by the powder gases in the chamber of the gun. The tubes A B and hoop C may be put together by hydraulic pressure or with shrinkage.

If the outer tube is to be shrunk upon the inner tube the builder can ascertain the exact amount to allow for shrinkage. Moreover, the continuously taper formation of the tubes greatly facilitates the uniform shrinking of one upon the other, a much lower temperature being required and the danger of injuring the tubes or hoops being much less than in the case of parallel tubes. The latter, unless the contraction of the outer tube is exactly equal or uniform at all parts, will be liable to have one end or part bind or become tight, while the other part or parts, still being free, as the tube continues to shrink will be drawn against very great frictional resistance toward the fixed end or part, thereby injuriously straining the metal; but with taper tubes this difficulty will not exist or will be considerably diminished. When the tubes or hoops are to be put together with shrinkage, it is preferred that they should be heated to a temperature not exceeding 300 degrees Fahrenheit. To facilitate the formation of the taper tubes and the accurate fitting of the one upon the other as above described, there is employed a mandrel which, in respect of its diameter and taper formation, is a counterpart or fac simile

of the inner one of the aforesaid tubes. The outer tube is so fitted to this mandrel that when removed therefrom and placed upon the inner tube it can be placed thereon with very little pressure within a short distance of its ultimate position, and can then be forced home with or without shrinkage, as above described. This method of at first accurately fitting the taper tubes to each other within a short distance of their proper relative positions and then forcing one tube home or expanding and shrinking it upon the other secures the liner in the gun in such a manner that, although it will not be liable to accidental displacement, it can be readily withdrawn when worn without injury to or displacement of the other tubes or hoops of which the gun is built up.

As an alternative to the use of a tube made in one piece continuously taper from end to end, the builder, in some instances, makes the inner tube-that is to say, the A tube, containing the liner, or the B tube, or other intermediate tube or tubes-in two or more continuously taper pieces or lengths, united by screwing the pieces together, the screw joints being made taper, with a plain or unscrewed portion at the end of each hoop to insure the proper fitting of the parts together, as shown in Fig. 1 or Fig. 4. It is obvious that this form of joint, for the purpose specified, is stronger and more reliable than an ordinary rabbeted or square shouldered joint, and it considerably facititates the connection and disconnection of the parts.

Sometimes wire is coiled around the liner a, so that when the liner is in its place there will be a space between it and the A tubes surrounding it occupied by this wire, which will afford a strong and elastic support to the liner, so that it can withstand the stresses due to the firing of the gun without being so tightly forced into the A tube as to make its withdrawal therefrom a very difficult operation. On the breech end of the liner is cut a screw thread, whereon is fitted a nut d. In the gun shown in Figs. 1, 2 and 3 there is formed for the reception of this nut a recess or cavity in the end of the A tube, as shown at c in Figs. 1 and 2. Instead of the nut there is sometimes formed on the liner a solid collar, which will enter the recess or cavity. The nut d can be screwed upon the liner before the latter is forced home in the A tube, and affords the means for insuring or assisting to insure the accurate adjustment of the liner to its exact position within the tube and prevents injury to the latter by forcing the liner too far into the tube-that is to say, the nut dor the solid collar, being in close contact with the bottom or end of the recess or cavity in the A tube, will limit the end wise movement or adjustment of the liner, so that in applying the pressure for forcing the liner into the tube no other precaution in respect of insuring its true position therein or preventing injury to the A tube will be necessary except to ascertain that the nut or collar is properly home against the end of the recess in the tube. Moreover, all danger arising from too great contraction of the tube in shrinking it upon the liner is avoided. The nut d, moreover, protects the screw thread at the rear end of the liner and can be readily unscrewed to permit the application of a device for removing the said liner.

The A tube at its rear end has provision for the reception of the breech plug ring f, which is screwed into the end of the tube and is so arranged that its inner end bears upon the rear face of the liner a and liner nut d. The breech plug ring has the usual segmental or interrupted screw threads to engage with similar threads on the breech plug. Sometimes the breech plug ring is split on one side, and one or more wedges or keys, g, are driven into

the aperture, as shown in Fig. 3, to tighten the ring in its place. By this device the removal of the ring is made easy-that is to say, instead of having to exert sufficient force to unscrew the ring while its screw threads are tightly engaged with those of the tube, the builder can draw out the wedge or key, g, and thereby slacken the ring f within the A tube, so that the ring can be very easily unscrewed. Suitable means are provided for securing the wedge or key in place and for turning the ring in screwing it into or out of the tube. The breech plug is usually cylindrical, but sometimes made taper, either with segmental or continuous screw threads, to facilitate the opening and closing of the breech. In some instances a hoop screw threaded internally is used, as shown at i Fig. 1, for securing together the adjacent ends of the hoop C and tube or hoop 2в, or of other tubes or hoops.

One important advantage arising from this construction is that the builder can make the parts interchangeable, so that if any part of a gun is injured or destroyed it can be readily replaced or renewed. Moreover, the invention affords the means for so constructing the gun that its various parts can be properly fitted together and then taken asunder and very conveniently packed for transport to any distant station, where they can with very simple appliances be again put together.

-The Iron Age, October 15, 1896.

b. Armor and Projectiles.

Tests of Armor Plates in the Witkowitz Iron Works.

On the 16th and 18th of September, 1896, in presence of a comission sent by the Imperial War Ministry (navy section) to Witkowitz, armor tests were carried on in the works there.

The object of the tests of the plates furnished by the Witkowitz works was a double one. In the first place, it was to be shown what progress the Witkowitz works had made in the preparation of ships' armor since the international tests conducted in Pola in November, 1893; and, in addition, a comparative test was to be made between a Harveyized special plate and an un-Harveyized homogeneous nickel-steel plate, the results of which are to serve as a guide in determining the Navy Department as to the armoring of a new ship.

It was assumed from the start that it would be possible to reduce the thickness of the plates, which had been fixed at 270 mm. as a maximum for the three coast-defense vessels Monarch, Wien and Budapest, then in course of construction, to 220 m. with the same strength of armor.

The plates 6402 and 6559 were tested with the Krupp 15 cm. gun, L/40, using steel armor-piercing projectiles, Provenienz Streiteben, which, judging by the appearance of the fragments were very hard and of excellent quality. The distance from the muzzle of the gun to the target was 59.8 m. All the shots were fired normal to the target.

The plate was held fast in a strong framework without bolts, on an oak backing 500 mm, thick, the wooden backing carrying in the usual manner two inner skins of sheet steel 12 mm. thick. The velocity of the projectile was measured at each shot, and the weight of the charge was accurately verified.

PLATE 6402.

The experimental special Harveyed plate, prepared by a process peculiar to the works, had the following dimensions: 1850 mm. long, 1475 mm. broad and 220 mm. thick.

The projectile was shattered into fragments, of which 49, weighing 30.5 kg. in all, were collected.

The plate received an indentation 92 mm. deep; over an area 270 x 285 mm. around the point of impact, on the face of the plate, the hard layer peeled off to a depth of 10 mm. The back of the plate remained unaltered and showed neither bulge nor crack.

Shot 2.-15 cm. steel shell L/3.2; weight 45.7 kg.

Velocity of impact.

Energy, total. .

Energy per cm. of circumference.

Energy per cm.2 of cross-section

5.461 mt. The projectile was shattered into fragments, of which 41, weighing 21.5 kg. in all, were collected.

The head of the projectile remained sticking in the plate and fell out at the third shot; the depth of penetration could then be measured and was found to be 100 mm. The material over an area 220 x 190 mm. peeled off to a depth of 10 mm. On the back appeared a bulge 46 mm. high, free from cracks. The plate showed neither crack nor flaw on face or back; the backing remained unimpaired.

Shot 3.-15 cm. steel shell, L/3.2; weight 45.5 kg.

Velocity of impact

Energy, total

Energy per cm. of circumference.

Energy per cm.2 of cross-section.

673.15 m. 1050.83 mt.

22.448 mt.

6.026 mt.

The projectile was shattered into fragments, of which 48, weighing 18 kg., were collected.

The point of the projectile remained sticking in the hole made by the shot, its measureable penetration 52 mm.; the border of the point of impact over an area 280 x 260 peeled off as in previous cases. On the back of the plate appeared a bulge 41 mm. high, free from cracks; the plate shows no other defects whatever, either on its face or back.

PLATE 6559.

The un-Harveyed homogeneous nickel-steel plate, prepared according to a process peculiar to the works, had the dimensions 1720 x 1720 x 220 mm.

Shot 1.-15 cm. steel shell L/3.2; weight 45.5 kg.

The projectile was shattered into fragments, of which 25, weighing 32.5 kg. were collected.

The point of the projectile remained sticking in the plate but fell out at the second shot, leaving the depth of penetration measureable at 125 mm. Around the point of impact, over an area of 240 x 270 mm, the material was pressed away, without causing any portion of the face of the plate to peel off.