CONTENTS. 



ESSAY UPON SINGLE VISION WITH TWO EYES. 



PART I. 



Of the different opinions concerning single vision with two 

 eyes j and principally of those of Dr. Smith and Dr. Reid 



pagel 



PART II. 



Of a new theory respecting visible direction, and of a solu- 

 tion hence derived of the question, why objects are seen 

 single with two eyes . . . .28 



PART III. 



Of some consequences from the foregoing theory of objects 

 being seen single with two eyes ; together with the ex- 

 planation of several other phenomena of vision . 51 



EXPERIMENTS AND OBSERVATIONS ON SEVERAL 

 SUBJECTS IN OPTICS. 



ARTICLE I. 



On visible position and visible motion . . 69 



