"وجهات نظر وآراء العميد جون جاكوب، قائد وسام الطُهر. مساعد النائب للملكة؛ مساعد النائب لحاكم الهند العام، وغيرهما؛ والقائد الراحل للقوات البريطانية في بلاد فارس؛ والقائد الحالي لخيالة السند غير النظامية، والمشرف السياسي على الحد الشمالي الغربي للسند." [‎٢‎٣‎٦] (٤٨١/٢٦٧)

236
of rifling adopted in them is the very worst possible. It is
only the two-grooved rijie in disguise. (See Fig. g.)
Let the shoulders of the grooves of a two-grooved rifle be
removed, as shown by the dotted line in the sketch, and
you have the Lancaster rifle.
But by the removal of these shoulders, the friction, if
the twist be considerable, becomes enormous: the ball
and the bore are not quite round, but nearly so ; wherefore,
as the ball is compelled to follow the twist of the bore, it
acts like a " cam," and endeavours to burst the gun; or
the dotted part in the sketch becomes a very acute wedge,
which the spiral motion causes to be driven with great
force into the bore as the ball is driven out.
The heat developed by the friction must be very great,
and the tendency of the gun to burst, or the shell to crush,
also very great.
It would be far better than this to use a four-grooved
rifle, with projections on the ball, even of iron, with a
greased leather patch.
One more remark appears requisite.
The twist I now use, and which I find best, is one turn
in thirty inches, or, better still, four-fifths of a turn in the
length of the barrel.
This I find to maintain the spiral motion of the ball
quite up to the last, in the long ranges attained by my
rifles ; and a rapid spiral motion is necessary to preserve
the light end of the ball truly foremost throughout its long
flight; which it is perfectly successful in doing.
The grooves should he full deep, and of breadth equal to
that of the lands; the bands on the balls or shells being
made to correspond so as to fit the grooves nicely, but quite
easily, with a greased patch round them. It may be well
to observe that thin cotton cloth, well washed to free it