1831.] 
An Essay on the Game of Billiards. 
179 
IX . — An Essay on the Game of Billiards. 
[Continued from p. 119.] 
Here, perhaps, it may not be improper to introduce some remarks on the merits 
of an opinion, that “ The angles of accidence and reflection are equal since 
it is advanced universally by the first authorities, and applied particularly by 
some, to the present subject, with a latitude of expression, not qualified by any 
exception, as might be expected when reduced to practice, if any were supposed 
to be ; and none having been made, the fairest inference follows — an opinion that 
none existed. Yet (with due deference), the most simple act, by which informa- 
tion can be had in this case, is also the most convincing proof, that the doctrine 
is not only erroneous, but, that its universality is more frequently destroyed than 
one instance shown in playing the game, where it is not fallacious. For, let a 
ball be struck or driven indifferently with any thing against the cushion, at an 
angle less than a right one ; and the lines of accidence and reflection marked : 
then reverse the stroke, by making the line of reflection that of accidence, and 
the ball will not be reflected in the other, but, in a line making the remote angle 
with the cushion considerably less, if not prevented by a twist. This diminu- 
tion evidently takes place from the rotary motions in aid of the progressive, and 
if their influence be not denied, surely either such concomitants of the progres- 
sive, as are almost physically inseparable from it, ahould be mentioned abstract- 
edly 5 or, admitted as giving no interruption to the universality of the doctrine, 
by being involved. But, to bear up the position in some measure, it may be said. 
Billiards (as a particular game) , should be excepted ; and that the doctrine will 
hold most completely in any other view. Is it then supported by the game of 
Tennis, when every Tennis-player knows how much the angle of reflection 
depends upon the manner of striking the ball with the racket ? If Tennis will 
be called a particular game also, it may be asked, what game is not particular ; 
and how many instances it will require, to unhinge the reception this doctrine 
has met with ? Let the position be carried still farther, to any projectile, from 
a cannon ball, to a common bullet ; if it obtains there, for what purpose are 
guns rifled, but, in order, by a twirling motion in a plane at right angles with 
the progressive, to diffuse the rotary tendency equally around, and thus correct 
the aberration of the ball, in its flight to the object aimed at : or if rotary 
motion be admitted, it is presumed similar causes will be allowed to have similar 
effects here also : for it is of no consequence, whether they proceed from a 
cue, racket, or gun-powder j the surface of a billiard-table, the floor of a tennis- 
court, or the barrel of a gun. Moreover, if the digression would not be thought 
too great, by infringing the department of metaphysics, the view might be extend- 
ed from palpable, heavy substances, to air and sound j and applied there with no 
better success : for, how can the particles whereof they are formed, after imping- 
ing upon a surface, be supposed to float, and roll along it, if the angles of lefiec- 
tion, be equal to those of accidence? or, how can a whispering gallery be 
accounted for on a principle which precludes the possibility of conglomeration ? 
But the hallowed ground, upon which (it is conceived) this doctrine, when ap- 
plied to light and colours, chiefly rests ; although it should be approached with 
still more circumspection j it is hoped, will not be thought profaned, by Bicker- 
ings of dark and tremulous conjecture. The co-existence, length of duration, and 
