10 AN ESSAY ON 



and its apparent direction from that eye, if 

 visible place be, in the language of Dr. Smith, 

 only an idea of real or tangible place, visible 

 direction must bear the same relation to tangi- 

 ble direction ; a consequence of which is, that 

 \ve can never have a more accurate knowledge 

 of the direction, in which an object may lie 

 from any part. of our bodies, by sight than by 

 touch. Facts, however, prove the contrary. 

 Let any person, for instance, taking a pin in 

 his hand, endeavour, without looking, to bring 

 its head upon a level with either of his eyes ; 

 and there are many chances to one but he will 

 fail in the attempt, of which sight will inform 

 him, when he turns his eye to the object. This 

 to me is a convincing argument, that external 

 bodies are not seen in certain directions, be- 

 cause they have been previously felt in them ; 

 and, consequently, that visible place, of which 

 visible direction is a component part, is not 

 merely a representative of the place perceived 

 by touch. But if the place, in which an object 

 appears to each eye separately, does not entirely 

 depend upon any lesson from feeling, the in- 

 ference is, that when an object appears in one 

 and the same place to both eyes together, nei- 

 ther is this effect to be attributed solely to the 

 informations of that sense. 



Thirdly, in whatever direction an object may 



