July 27. 1888.] 



SCIENTIFIC NEWS. 



93 



the white molten steel into the pit. The immense con- 

 verter ceased its roaring as it turned over, the infernal 

 stream poured forth, and in little more than sixty seconds 

 the mould was full. The metal was poured into a 

 " gate " or pipe that ran to the bottom of the mould, so 

 that the steel entered the mould at the bottom and 

 welled up to the breech at the top. 



For half an hour there was nothing more to be done. 

 Then the pit was surrounded by anxious faces, and the 

 superintendent, his eyes shaded, peered into the hole. 

 His long experience in steel making enabled him to take 

 in at a glance many signs of success that would have 

 been hidden from any one but an expert, and he pro- 

 nounced the " cast " a success as far as it had gone. As 

 to the quality of the steel he must wait for it to cool 

 before he could give an opinion. The total length of 

 the casting over all was 276! inches. The sinking head, 

 which was made in two diameters, was 72 inches in 

 length. The part immediately above the gun, which 

 was 48 inches long, was i6| inches in diameter at the 

 top and 17 inches at the gun. The smallest section, 

 which was 2 feet high, was 15 inches in diameter at the 

 bottom and 14! at the top. 



The finished length of the gun will be I93'53 inches, 

 the total weight of the metal 18,490 pounds, the 

 length of the pattern for the gun proper being 204$ inches. 



The gun was in the mould five days. At the end of 

 that period it was cool enough to be removed. A very 

 thorough examination of it was then made, every inch 

 of its surface being closely inspected, and several pieces 

 cut off the sinking head for chemical tests. Not a flaw 

 could be found, and the experts who were permitted to 

 examine the gun declared it to be a perfect piece of 

 Bessemer. 



The next process was the rough boring. The solid 

 cone was placed in a lathe, and a tool of the finest steel 

 began to cut a tunnel through it, beginning at the 

 muzzle. The bore was Sj inches in diameter. For 

 over a week the tool went through the hard steel, the 

 turnings being carefully preserved and tested at intervals. 



These tests showed the steel to possess in a remark- 

 able degree the qualities which are essential The result 

 of a test made upon a piece of the metal cut from the 

 angle of the trunnion showed : — Ultimate strength, 92,700 

 pounds; elastic limit, 51,960 pounds; elongation in 2 

 inches, 12J per cent. Samples taken during casting 

 under cold bending tests, gave the following results : — 

 Pieces forged from 2-inch square ingot to § inch square, 

 and allowed to cool, were bent cold to an angle of 161 

 degrees without fracture. 



As the bore was cut through it was carefully watched, 

 an incandescent electric light bulb being used to examine 

 the interior of the gun when the cutting tool was with- 

 drawn. Two or three hours was sufficient to dull the 

 edge of the tool, and it had to be taken out and ground 

 at frequent intervals. The time when this became 

 necessary was unerringly indicated by the heating of the 

 gun caused by undue friction. At last the bore was cut 

 through, and nothing but satisfaction could be expressed. 

 The Government inspectors were at the mill every day, 

 and it is safe to say that the big gun received as close 

 attention as any mother vouchsafed to her first babe. 



Now came the annealing. This was a delicate opera- 

 tion, and upon its results depended very largely the 

 success or failure of the gun. A bricked up furnace, 

 deep enough in the ground to enable the gun to be 

 placed in it muzzle downward, with but a few feet above 



the surface, was prepared. Into this the gun was care- 

 fully lowered. Then it was slowly heated by natural gas 

 to a temperature of 1,400 degrees, allowed to cool, again 

 subjected to the 1,400 degrees, and again allowed to cool. 

 It was in the annealing that Mr. Hainsworth made his 

 boldest departure from the accepted methods of preparing 

 steel for trying work. In talking about it the other day 

 he said : — 



"We do not use the old-fashioned oil tempering 

 process. Oil tempering has been tried in England, and 

 it is an open question whether oil does or does not 

 temper steel. By our process we can give the steel used 

 in the 'chase' or barrel of the gun ductility, and that in 

 the chamber excessive toughness. Steel guns tempered 

 with oil are liable to develop weakness in the ' chase.' 

 We have our process thoroughly under control, and can 

 give the steel special physical characteristics as required 

 in different parts of the gun. Thus, in the ' chase,' we 

 want ductility supremely, while in the chamber tensile 

 strength and elasticity are mainly required." 



The claim made by Mr. Hainsworth for his annealing 

 method was thoroughly borne out by the result of the 

 process in connection with the gun. In about a fortnight 

 from the time it was placed in the annealing furnace it 

 was taken out and placed in the lathe once more. 

 Scarcely was it secured when workmen attacked the test 

 pieces around the trunnion with cold chisels. The re- 

 sistance of the metal to the chisel was greater than the 

 men had ever experienced before, and many were their 

 admiring comments as they chipped and chipped away. 

 It needed but a superficial test of the pieces thrown off 

 from the trunnion to show experienced men that the steel 

 was as tough, close, and smooth as could be desired. 

 The men next went to work at the breech, cutting off a 

 portion of the sinking head to be subjected to official tests 

 in Washington. Ere the test piece was quite severed from 

 the breech Lieutenant Eaton, the Government Inspector, 

 placed his mark upon it and authorised it to be cut off. 



AtWashingtonitwill be rifled, polished, and'made ready 

 for the firing tests at Annapolis. There will^be no child's 

 play, and the gun will not be humored in any way. It will 

 be loaded up with a one hundred pound ball and as much 

 powder as can be forced in at the breech and touched off. 

 This will be repeated as fast as the gun can be charged. 

 Ten shots in eleven minutes is the rate at which it is 

 expected the gun will be fired. The contract requires 

 that the ball shall travel at the rate ef 2,000 feet a second 

 as it leaves the muzzle, and, to attain this velocity the 

 pressure upon the gun will be tremendous. If the gun 

 is as good as its maker believes, it will stand this ordeal 

 without a sign of weakness. It is tested to stand a 

 pressure of fifteen tons to the inch at the breech and five 

 tons to the inch at the muzzle. 



Supposing that the gun passes the regulation test 

 satisfactorily, it is expected that it will be put to still 

 severer tests, each one greater than the last, until it blows 

 to pieces. The gun will be lost, but it will convey a 

 lesson in the manufacture of heavy ordnance that it is 

 hoped will be worth millions of dollars to the people of 

 the United States. 



The contract price for this gun, which will be paid only 

 in the event of its withstanding all tests, is 3,300 dols. A 

 built-up gun of the same calibre would cost 22,000 dols. 

 These figures speak for themselves, proclaiming un- 

 mistakably the revolution in gunnery that will take place 

 if solid steel cannon become the ordnance ^f the world, 

 — New York Herald. 



