12-LNCH STEEL В. L. RIFLED MORTARS.	65
TABULATION OF STEEL TENSION SPECIMENS FROM 13-INCH STEEL B. L. RIFLED MORTARS.
STEMS OF SPECIMENS, 3״ LONG, 564.״ DIAMETER.
No. of test.	Position in gun.	Location of specimens.	Elastic limit per square inch.	Tensile strength per square inch.	; Elon- ga- tion.	Contraction of area.	Appearance of fracture.	Remarks.
7303 7354 7370 7402 7403 7406 7298 7306 7356 7357 7371 7405	Tube	 	do	 —do	 —do	 —do .... —do	 Jacket... —do — — do — —do	 —do	 —do		Outside. Middle . Outside. —	do ... Middle . Outside. Miadle . Outside. —	do ... Middle .	Pounds. 51.000 55.000 51.000 55.000 55.000 45.000 49.000 53.000 51.000 49.000 51.000 51.000	Pounds. «90,400 100,480 92,320 92.400 80,080 81,680 92,090 88,960 89,880 87,200 88.400 91,680	Per etiti. Z 18.7 18.3 19.7 26.0 21.3 22.0 24.0 19.7 21.7 24.0 21.7	j	Per ct. 39.2 24.6 49.7 52.2 47.2 45.5 49.7 36.4 49.7 49.7 49.7	Granular,SOpercent; silky, 50 per cent. Granular	 Silky	 	do	 	do	 	do	 	do	 Siiky, granular spot Siikv	 	do	 	do		Breech end. Do. Do. Muzzle end. Do. Breech end. Muzzle end. Do. Breech end. Do. Do. Muzzle end.
־־Specimen not fractured; stripped the thread on head.
Gas Check Disks for 12-inch Steel B. L. Rifle.
Marks.	Diam- eter.	Sec- tional area.	Elastic limit per square inch.	Tensile strength per square inch.	Elon- ־*$. tion.	Contraction of area.	Appearance of fracture.	Elongation of inch 1 sections.:
1 2 4	Inches. .505 .505 .505	Sq.inch. .20 .20 .20	Pounds. 75.500 94.500 76.500	Pounds. 145,100 162,900 152,500	Per ct. 14.0 6.5 11.5	Per ct. 27.4 9.5 16.9	Fine granular, silky spot.. Fine granular, silky spot at circumference. Fine granular, silky spot..	// // . 20*,. 08 .05, .08* .08, .15
6	.505	.20	75,000	143,750	13.0	16.9		do		* ' Л0,Л .16'
								
H. Doc. 508----5