English Amateur Billiards Association

EABA : The Billiard Monthly : April, 1912

The Billiard Monthly : April, 1912

Our Readers in Council

The Naming of Ball Aims

To the Editor.

In your last issue you publish, under the above heading,
a letter from me which I wrote in response to your request
for correspondence on the subject.

In a foot-note to the letter you remark that “Col.
Western does not say in his book that a seven-eighths ball
is a grazing ball.” As I neither accused him of doing so
nor so defined it myself, your comment was evidently made
under a misapprehension.

I fully endorse your opinion as to the value of Col.
Western’s book, but on this question of aims he merely
reverses the old naming of the finer and fuller than halfball
aims, and I still submit that the old way is the better.

Up to the present we have directed our one-eighth, quarter
and three-eighths ball aims to points in space; Col.
Western does the same thing for his five-eighths, three-quarter,
and seven-eighths aims.

It appears to me more consistent to have a thick contact
by a three-quarter aim than the thin one which Col.
Western’s method gives.

On page 3 in reply to question 122 you say that the
objective point “is always (except in full ball strokes) just
twice as far from the centre of the object ball as the desired
point of contact.” Permit me with all deference to
point out that this is quite a fallacy, although it is frequently
mentioned.

For instance, the contact of a half-ball aim is not at a
spot on the circumference of the object ball midway between
the point aimed at and the point cut by an imaginary line
connecting the centres of the cue and object balls. The
contact is nearer the latter point and, of course, its position
varies according to the distance between the balls.

A. LONG BROWN.

Muswell Hill, N.

March 25, 1912.

[Our only point with regard to Col. Western’s method of
naming all aims in proportion to their distance from the
centre is that this seems to us to be the only strictly mathematical
and coherent method. As to the half-ball and other
aims and contacts, the whole quarter of the circumference
of the object ball is not seen when aim is being taken. It
is the division of what is seen that matters and to this the
rule of aiming twice as far from the centre as the intended
point of contact applies at any distances. That this is
found to be correct in actual professional practice is set
forth by (amongst others) Stevenson in his “Top of the
Table Game.”]
What is Elasticity?

To the Editor.

In last month’s Billiard Monthly you say:—
Tests revealed clearly the fact that bonzoline balls are
less elastic than crystalates, that crystalates are less elastic
than hard (or African) ivory balls, and that soft (or
“Indian”) ivory balls are the most elastic of all.

Among various definitions of elasticity, perhaps the following
from Chambers’s Encyclopaedia is as good as any:—
Elasticity is that property of matter which enables a
body, whose form or bulk has been changed by a force
to support without disintegration or further yielding the
continued action of that force, and to recover its original
form or bulk when left to itself.

When the cue ball strikes the object ball, a very slight
flattening of both balls is the immediate result, at the point
of contact. I will assume the force is not sufficient to
break the balls, or crack them, or injure them in any way.

Then immediately the elasticity of the balls comes into play.

They tend to, and do, recover their original form, and the
more effectively and the more rapidly they recover their
original form, or shape, or sphericity, after the temporary
slight flattening at the point, the more elastic they are, and
the more effectively and rapidly they recover shape, the
wider the angle at which the cue ball will be thrown off.

Play with two balls of some acknowledged inelastic substance
such as clay, or lead. You will find the throw off
of the cue ball less than that of Indian ivory. We must
make the experiment of course with the same contact, or
angle, say a true half-ball stroke, and you will find that the
less elastic the substance, the less the throw-off, i.e., the
less wide the angle of the cue ball. And so I think on
investigation you will find that the greater the elasticity the
greater the throw-off.

The greatest throw-off is with bonzoline, so I should
say the most elastic balls are bonzoline and the less elastic
are crystalate, and the still less elastic are ivory.

Your paragraph suggests that your view is that the less
the throw-off, the greater the elasticity. My view is that
the greater the throw-off, or the wider the angle, the greater
the elasticity. May I say without offence to your “professional
billiard expert” that he probably knows more about
practical billiards than he knows about the theory of elasticity.

Another definition of elasticity from “Ganot’s Physics”
is:—

Elasticity is the property in virtue of which bodies resume
their original form or volume when the force which
altered that form or volume ceases to act.

But your paragraph puts it the other way and I venture
to think it is wrong.

H. C. W.

[You are quite correct; and if billiards were played
with india-rubber balls the throw-off would be greater still.
In billiards the “give” of the ivory balls has, to some
extent, been made a convertible term for “elasticity.”
Hence the confusion in terms.]

Contact Detail

You can contact us by clicking the button below we will do our best to return you email as soon as possible.

Policy and Rules

All our rules and regulations are available in the following section. Please click below for further details.

Membership

You can now apply for membership of the EABA online and pay for entry into all our tournaments.