Our Readers in Council

Scientific Billiards.—A Few Points

To the Editor.

With reference to Mr. Long Brown’s letter, and your
footnote in the June issue, perhaps I can help. Both are
quite right. The variance is that you measure in different
manners. Mr. Long Brown measures round the circumference
of the ball, and you on the radius or diameter of the
ball. In the case of the half-ball the distance of the point
of contact from the nearest point of the circumference of
the ball, from which Mr. Long Brown measures, is only
one-third of the circumference to the aiming point, which
is the edge of the ball, but it is half the radius measuring
from the centre of the ball.

If Mr. Long Brown will drop perpendiculars from the
points of contact on the diameter of the object ball in Figs.
2, 2a, and 2b, pages 13, 14, and 15, of my book, he will, I
think, see what you mean by your footnote, which is also
correct.

With reference to Query 155 in the same issue asking
whether it is possible to make a right angled screw at a
finer than half-ball contact, it will be seen on reference to
Table 9, page 97, in my book” Practical Science on Billiards,”
that with a 5/8 contact with 60 per cent. of screw the
angle is 94 deg. 27′; and with a J contact and 70 per cent.
of screw the angle is 91 deg. 3′, and, of course, it could be
carried further. It is possible theoretically, but these
amounts of screw are difficult to put on.

With reference to Query 153, asking whether for a finer
and fuller than half-ball shot, the aim is taken at the same
distance off and on the object ball, in order to get the same
direction for the cue ball, the answer will be found in
Chapters V. and VI.; and graphically so in Chapter XII.
of my book. Approximately it is the case, but not exactly.

With regard to “W’s” lucid article on “Why the Half
Ball is the Amateur’s Sheet Anchor,” I would suggest that
the amount of variation due to error will possibly be found
more clearly set forth in Chapter XII., headed, “On, the
proportionate variation in direction of the cue ball, due to
the division of the object ball it strikes,” and in Figs. 24,
24a, 25, 26, and 27, rather than in Figs. 15 and 18 to
which he refers. And in his reference to the clock face, it
must be remembered that the point of divergence of the cue
ball, and not the centre of the object ball, is the centre of
the clock, and that the centre of the object ball must be
supposed to be on the circumference of a little circle struck,
with 2 1/16 inches radius from the clock centre.

C. M. WESTERN, COL.,

Author “Practical Science of Billiards.”