LOOKING THROUGH THE HAND. 



is of two separate moons, each complete, 

 though small, which exhibit between them 

 four horns. 



When the eyes happen to converge to the 

 point D, the images for the two eyes reach out- 

 wards from the centres of the two fields of 

 vision. The brain sees these two centres as 

 one point in space, so that the two moons 

 appear to touch, possessing in the middle 

 one horn-point in common, and a separate one 

 at each end, so as to make three horns alto- 

 gether. 



Thus is justified the poet's hesitation to 

 decide, not between two and four, but between 

 three and four, as the number of the moon's 

 horns. 



3. Looking through the Hand. 



Hold a roll of paper in the left hand, and 

 putting it up in front of the left eye, look 

 through it at some bright object at a distance, 

 such as a picture on the opposite wall. Hold 

 up the palm of the right hand in front of the 

 right eye, so that the edge of the palm is against 

 the side of the roll and about 6 or 8 inches in 

 front of the eye. 



The palm of the right hand might be ex- 

 pected to block the view of the right eye, 

 but instead of that the observer feels that he 

 is looking right through a hole in the right 

 hand, somewhere in the position of the dotted 

 p 225 



