394 
MINUTES OF PROCEEDINGS OF 
of pressure between tlie ribs and grooves, lubrication may be used. 
Practically, so far as rifling is concerned, both gun and projectile are 
everlasting. 
The following table will serve for comparison of the probable pressures 
which produce rotation, and are wasted in friction, with the various 
systems of rifling. They are all calculated for a twist of one turn in 40 
calibres, so that those given with Whitworth's rifling would have to be 
doubled for one turn in 20 calibres adopted by him. The pressures in 
italics are those due to exceptionally high pressures. 
j 
Systems of 
rifling. 
600-pr. gun. 
1200-pr. gun. 
Bearing 
surface 
inches. 
Pressure on studs. 
Longi¬ 
tudinal 
pressure 
wasted 
per cent. 
Bearing 
surface 
inches. 
Pressure on studs. 
: Longi- 
' tudinal 
pressure 
wasted 
per cent. 
Total 
tons. 
Per 
sq. in. 
tons. 
Total 
tons. 
Per 
sq. in. 
tons. 
I • r uniform twist.... 
5 
90 
18 
14 
7 
j 180 
26 
If 
Hi » 
5 
225 
45 
2 
7 
450 
65 
2 
: £ <j 1 in 100 to 1 in 40 
3 
45 
15 
4 
90 
23 
n 
[81 
3 
111 
37 
2 
4 
225 
5$ 
2 
to 1 in 40. 
3 
60 
20 
n 
4 
120 
30 
if 
„ 
3 
60 
20 
i\ 
4 
120 
30 
*f 
Whitworth hexagonal 
120 
240 
2 
4 
170 
480 
3 
44 
120 
600 
5 
5 
170 
1200 
71 
5b 
Scott . 
4-5 
90 
2 
14 
60 
180 
3 
n 
„ . 
43 
225 
5 
ib 
60 
450 
74 
2 
Lead-coating. 
— 
— 
10 
- — 
ggffij 
— 
10 
Proposed rifling ... 
240 
[ 90 
x 
540 
180 
4 
1, 
FI 
240 
225 
6" 
1 
540 
450 
1 
\ 
** 
There are some other points which may be considered more in detail. 
It may be thought that the expense of cutting so great a number of 
grooves in each shot will be considerable; but in the opinion of a very 
able practical engineer and mechanic,* this would not be the case, for a 
i/f On this point, Dr. Anderson, Superintendent of Machinery, War Department, observes in a 
letter to the writer, 12th May, 1873, “If the pi’ojectiles were to be done in large numbers, so as to 
make it worth while to provide self-acting tools to act with a number of cutting instruments simul¬ 
taneously, the cost for wages would be very trifling, requiring one quarter of an hour of unskilled 
labour. Of course, the size would have an influence, but the cost would not be any barrier to the 
system if it is right in other respects.” 
