5T6 Mr Charles Beil m the Motions (^' the Eye. 
society of Edinburgh around him, can be so totally ignorant of 
this subject ? When a man stands or sits, he exercises the ten- 
sion of the whole muscular frame, to the motions of which he 
is minutely sensible, and without which he would fall like one 
dead or drunk. He stands or walks by a fine adjustment of the 
muscles to the balancing of the body. It is quite obvious, that 
he cannot do this, without a consciousness or sense in the mus- 
cular frame. It is by the same power that he knows the posi- 
tion of his body, whether in motion or at rest. If he be twitched 
round, violeixie is done to these balancing powers, and a distur- 
bance occasioned to the muscular system, which gives him as live- 
ly a conviction of the change, as if it came to him through all the 
five senses. And, if placed upon a stool, although the experi- 
menter should be so careful as to apply a leathern belt, and an 
assistant to turn him round, he will be conscious of such verti- 
cal motion ; and whether he closes his eyes the while, or not, he 
will be conscious that he is turning, by a succession of lesser 
motions, to the four sides of the room ; and if there be an im- 
pression of an image on his eye, it will appear to be on that side 
of the wall to which he has turned. 
It is ill the course of the same singular mode of argument 
that Dr Brewster thus expresses himself. “ Let the observer, 
with a spectral impression on his retina, close his eye, and turn 
round his head, either in a vertical or a horizontal plane, by the 
muscles c^'his nech alone. It will now be found, that the spec- 
trum follows the motion of the head ; and hence we must con- 
clude, that the motion of place or relation depends on the exer- 
cise of the muscles of the neck, as those of the eyeball have 
been entirely at rest.” If it were not addressed to this learned 
Society, I should imagine he was here trifling with us. If a 
spectrum upon the eye appears before us, it will continue before 
us in whatever way we turn ; and, I have little doubt, I shall 
be excused for not having said so in my original paper. 
I repeat, that, what I conceived it necessary to prove was, 
that the eye, with its apparatus of muscles, has the power of 
conveying the idea of the phantom in different positions, accord- 
ing to the operations of its muscles,, and independent of the mo 
tions of the head or body. 
By the extraordinary resistance of a man of Dr BrewsteiV 
