THE ROYAL ARTILLERY INSTITUTION. 
413 
Hardness of Studs. 
Copy of a Beport from the Superintendent, Boyal Gun Factories. 
Royal Gun Factories, 
Woolwich, 17. 7.’65. 
Sir, 
With reference to your letter of 3rd June 1865, Min. 15,560, I beg to 
forward copy of Report of Experiments made to show the hardness of the metal 
for studs of 7-inch projectiles, and to request that the specimens be carefully 
returned. 
I have, &c. 
(Signed) F. A. CAMPBELL, Col. R.A., 
Superintendent. 
Dimensions of Specimens. *"375 square and *"75 long. 
Nature of 
metal for 
studs. 
g 
Weight 
Nature of 
projectile. 
•§>° 
Mark of 
specimen. 
applied. 
Tons per 
square in. 
Permanent 
compression 
in inches. 
Remarks. 
Sir William Arm¬ 
Copper . 
7075 
1 
10-44 
•0005 
strong’s shunt 
15-5 
•001 
(100 lbs). 
17-08 
•003 
20-09 
•038 
30-06 
•272 
a 
n . 
7076 
8 
16-12 
•001 
17-72 
•0035 
20-09 
•0395 
French (110 lbs.) 
Zinc. 
7077 
121 
30-06 
6-06 
•2965 
•0035 j 
On this weight being 
17-08 
applied the speci¬ 
// ••••••••» 
7078 
125 
4-11 
•003 
men was broken. 
10-44 
•2065 
„ (100 lbs.) 
n *. 
7079 
225 
4-74 
•0035 
10-44 
•194 
// // 
n 
7080 
226 
3-8 
•0035 
10-44 
•164 
Major Palliser’s 
Gun metal 
7081 
0 
7-91 
•001 
(100 lbs.) 
12-18 
•0035 
20-09 
•03 
3006 
•085 
40-1 
•1375 
60-0 
•1875 
6-8 
•001 
n 
// 
7082 
26 
10-11 
•0035 
20-09 
•053 
30-06 
•114 
40-1 
•1685 
50-0 
•2205 
It does not follow that the hardest metal will offer the maximum resistance 
to abrasion; probably the zinc when rubbed against another metal through 
the medium of a lubricant under a pressure less than its elastic resistance 
may be the best to resist abrasion. 
(Signed) F. A. CAMPBELL, Col. B.A. 
17. 7. *65. Superintendent. 
To the Secretapy 0. S. Committee. 
