NovEMBER I, 1906| 
NEARER TS 9 
“ 
not believe ‘‘ anyone (bowling as is usual twenty- 
one yards or le SS) can get the swerve unless he over- 
pitches the ball.’ The facts seem to be that for 
right or left swerving it is essential to have a cross 
wind blowing, a long-pitched ball, and some initial 
spin with the seam vertical, but not too much of it. 
It is difficult to believe that the air’s resistance can 
effectually destroy this spin, seeing that the air has 
apparently very little effect in cutting down the spin 
which ultimately produces the break. The very fact 
the ball in addition to gravity 
according as there is 
under-spin or over-spin. Probably most ‘bowlers have 
an average amount of spin which they put on the 
ball. This will give what the batsman regards as 
the normally pitched ball of that bowler. Suppos 
this. normal spin to be over-spin. Then it is 
clear that if the bowler diminishes the over-spin 
or gives an under-spin the pitch (other things 
being equal) will be lengthened, but if the over-spin 
is increased the pitch will be shortened. Again, 
if the normal spin is under-spin, 
a diminution of that will make 
Fic. 2 —J. Tunnicliffe securing a one-handed catch high up in the slips. 
and Fielders.”” 
that the ball is projected with a smaller 
with will mean less effective frictional moment acting 
on the ball. Stokes, in fact, agreed with Tait that 
the frictional decay of spin in the case of a golf ball 
might be neglected to a first approximation, and we 
may assume the same for a cricket ball. 
There is not the least doubt that spin with the 
seam vertical must produce ‘‘ vertical swerve ’’ to 
some extent, a downward or upward force acting on 
NO. 1931, VOL. 
ae 
if) 
spin to begin | 
the ball appear to drop shorter 
than the expected normal pitch. 
This is obviously one way of 
varying the pitch, and one which 
must be very deceptive to the 
batsman. This way of stating 
it might seem at first sight to 
be inconsistent with Spofforth’s 
remark that ‘‘ the vertical spin, 
unlike others, must have exces- 
sive check spin, which naturally 
impedes the flight of the ball 
from the start, and keeps it back 
from its true destination.’’ It 
is difficult to see how check-spin 
can keep the ball back from the 
start. So far as motion through 
the air is concerned, there will 
be just as much retardation with 
the over-spin rotation as with the 
under-spin rotation. The word 
check-spin is, in fact, unfortu- 
nate, suggesting that it not only 
checks the progress of the ball 
after it strikes the ground—and 
that is the origin of the name— 
but also that it checks the ball 
as it moves through the air. In 
all probability the bowler, when 
putting on excessive check-spin, 
projects the ball with a some- 
what smaller velocity than the 
motion of the arm would imply. 
The hand, in fact, must get 
ahead of the ball, as very clearly 
indicated in one of the photo- 
graphs of R. O. Schwarz. With 
a pronounced under-spin a 
smaller velocity of projection is 
needed for a given length of 
pitch than when there is no spin, 
and the velocity of projection is 
less than what the motion of the 
arm would suggest. Hence the 
feeling of a retarded ball both to 
the bowler and the batsman. 
The direct effects of varying 
spins upon the trajectory as de- 
scribed above are true only when 
other conditions are the same, 
such as the velocity of projection 
and the height of the point of 
projection; but in giving diffe rent amounts of spin 
to a ball it is evident that these other conditions can- 
not be always the same. The conditions of the 
problem are indeed difficult to state, and one great 
merit of Mr. Beldam’s action photographs is that 
they throw so much light on the way in which the 
ball leaves the hand. 
ie the outstanding difficulty is to explain the right 
- left swerve, and the action photographs give little 
From “‘ Great Bowlers 
