AN ESSAY ON 



occupied. In this experiment, no real change 

 can be supposed to have occurred in the posi- 

 tion of the distant object ; and had any hap- 

 pened with respect to either the eye or the hole, 

 the object would not have been seen through 

 the latter. No other fallacy, therefore, exists 

 here, than that things, which are truly at rest, 

 appear, notwithstanding, to be in motion. 



The argument, which I have mentioned may 

 hence be derived against my theory, is this : 

 The visible directions of objects, in the optic- 

 axis which remained fixed, were formerly said 

 to be altered, because a new state of muscular 

 exertion was required to keep it so, in every 

 different degree of the inclination to it of the 

 moveable axis. But in the last experiment, 

 there seems no good reason for supposing any 

 change in the inclination of the moveable axis 

 to the other ; for, as one eye is closed, the 

 obvious intention of directing the two axes to 

 the same object, which is, that we may see it 

 single, no longer exists. If then an apparent 

 lateral motion be, in one instance, observed in 

 objects truly at rest, without any change of the 

 interval of the pupils, may not every other 

 motion of the like kind be also independent 

 of the muscular actions, which regulate that 

 interval ? 



Itisevident, that this argument rests altogether 



