118 ANNUAL OF SCIENTIFIC DISCOVERY. 



them, and with greater protection than in monitor turrets; a great 

 reduction of weight, which is in the lower part of the vessel ; the 

 total weight of a battery, with a wheel 20 feet in diameter and fit- 

 ted to receive 2 guns of 13-inch bore and 13 feet long, greatest 

 diameter 41^ feet, is 134 tons; ventilation is better secured than 

 by any other plan : 2 or 3 batteries can be placed in a single ves- 

 sel. This battery is also admirably adapted for land batteries for 

 harbor and coast defence. 



Ample experience has proved that the recoil and movement of 

 the wheel do not interfere with the accuracy of the aim; the shot 

 leaves the muzzle before the movement of recoil commences. It 

 will soon be tested in Boston harbor with 2 guns of 13-inch bore, 

 the use of which has been granted by the U. S. government. 



WHITWORTH ORDNANCE. 



Some time ago we described and illustrated Mr. TVhitworth's 

 plan for compressing steel immediately after its being run into 

 moulds for the manufacture of cannon, hollow projectiles, and va- 

 rious other~articles. Another patent has since been added to those 

 previously taken out by Mr. Whitworth, and experiments are now 

 being made at the Charlton Street Works for perfecting this im- 

 proved treatment of steel in making ordnance. A hydraulic press, 

 capable of exerting a pressure of 2.000 tons, has been laid out for 

 this manufacture. The steel manufactured at the Charlton Street 

 Works is all made in pots, and melted in coke furnaces; but the 

 introduction of Siemens' gas-furnaces is now under consideration, 

 and will in all probability be effected at an early date. The re- 

 sults of experiments hitherto made of casting steel under great 

 pressure, or rather of compressing steel in its liquid state, have 

 been most satisfactory. The entire absence of air-bubbles and 

 spongy parts in the metal, and the strength of the steel so pro- 

 duced, give to these castings the same nature and character which 

 steel acquires by the process of hammering or rolling. Engi- 

 neering. 



PUNCHED STEEL GUNS. 



The new mode of manufacturing seamless steel tubes for ord- 

 nance or other purposes, promises to be largely adopted. The 

 punching is done with a fine-pointed punch in the first place ; the 

 hole being started at both ends of the block, and the punch driven 

 in till the two holes nearly meet in the' centre. Blunt punches 

 of a larger diameter are then driven in to expand the hole, and 

 t!:c diaphragm separating the two holes is forced out. This opera- 

 1i"ii at once reveals any defect in the metal by the severe strain 

 ] i:t upon the grain, and so enables a defective block to be rejected 

 l,t tore any further labor has been wasted upon it. The hollow 

 ( \ liudi rs thus formed are heated and a mandrel inserted in the 

 l.olc, aiid they are then drawn out under a hammer into tubes, the 

 pivsLMiee of the mandrel making the thickness of the metal acted 

 upon very small compared wiHi a solid forging o f the same size, 

 thereby securing a more thorough working. The tubes are again 



