1831.] 
An Essay on the Game of Billiards . 
119 
on the same account likely to be reflected by their mutual elasticity, hopping 
or ricocheting frequently, as it advances ; so that the walk thus produced cannot 
be very great, though often supposed otherwise, when the ball after hitting another, 
moves with a celerity not much retarded. This, however, should be ascribed to a 
different cause, and is the consequence of their centres not being opposed in an 
horizontal line, at the time of contact j but let it be remarked, the centre of gravity 
lying above the line of direction, if the point of the cue be rough, and the ball, 
therefore, cannot disengage itself, at the instant of reflection from the table, the 
result must be the contrary. The same expedient by which a foul stroke may be 
prevented in playing for a twist, will serve here likewise. 
It may also, from appearance, be supposed, that the walking is greater than the 
twisting power, because the ball has more motion after hitting j but this is a mis- 
take, and takes place from confounding it with those of attrition and progression, 
which concur in carrying the ball forward ; whereas, the other power moves in op- 
position to them, and unassisted by any co-operating aid, till, combined with the 
re-action of the ball played at, those allied forces are overcome, and it returns 
with the difference. Besides, to give effect to either, in every degree ; since the cue, 
as has been shown, should be cut, prepared, and relatively applied, precisely in the 
same manner, over surfaces equal and similar, and sometimes the same ; 
turning the point respectively, because the objects are different, with every thing 
else in common between them, it may be concluded, that (abstracted from these 
intervening powers) both are equal. \ 
A lateral twist or rotation also, may be given, by striking the ball sideways 6 , 
with the point of the cue chalked as before : and though the effect be not easily 
discerned, in progression, it is very sensible in the angle formed on reflection from 
the cushion, the check it receives from thence, changing the centre of this twist or 
rotation, to the point of contact ; for, suppose the ball divided into an indefinite 
number of horizontal planes, and three of those, represented by three concentric 
circles (see Fig. 11.) on one of which the curved arrow is intended to exhibit this 
lateral rotation, given to it by the cue, a , b, in a direction at right angles with the 
cushion, c, d ; and supposing this effect equally distributed through all its parts, in 
proportion to their distance from the centre respectively, as has been before ex- 
plained ; then, while the chord e, /, describes the arc e, g, the diameter at h , is 
advancing to *, and will arrive afterwards at k t through which point, or with 
a deviation from it, according to circumstances, the ball will be reflected. The 
two inferior planes are precisely (as it may be seen) in the same predicament, and 
so is every other one whereof the ball is composed. 
6 A ball played in this manner often serves to a good purpose, when the cannon ball 
is within the bulk, and neither far from the string-line, nor near to a side-cushion, 
after both white balls have been pocketed, or oft' the table \ for, by playing back 
against the end-cushion opposite, in the usual way, the danger of going out of the 
balk, from the application of too much force, prevents the use of a sufficient degree, 
to send the ball so high, on its return from the balk-end, as the player might like. 
Hut, if he should strike the ball thus, against that part of the side cushion, just beyond 
the string-line, it will return within it, and occupy a place high enough, to command 
a good losing hazard in one of the corner pockets ; and in some situations with the 
adversary’s ball in the balk, a cannon may be expected with confidence, if the 
player be accustomed to the stroke. The farther from the cushion played against, 
the ball is laid on the string-line, the better ; for the interior angle will be greater, 
and the stroke therefore more efficient, or less of it necessary to accomplish the same 
design,— (See additional note in Appendix.) 
