NATURAL THEOLOGY. 61 



of the eye. Dr. Herschell, the celebrated astrono- 

 mer, while pursuing his nicest observations, was in 

 the habit, it is said, of practising upon this very prin- 

 ciple ; that is, of covering his eyes in the day, to in- 

 crease the sharpness of his sight in the night. 



It has been often noticed, that the pupil of a cat's 

 eye, and that of several other animals, is not round, 

 like our own, — but it is in the form of a long slit, 

 reaching from the top to the bottom of the eye. It 

 is made in two parts, like the sliding doors of a mod- 

 ern parlor, so as to admit of a close joint to exclude 

 the daylight entirely ; or, of being wholly drawn 

 back, so as to leave no obstruction to the light, in 

 the dark places the animal loves to frequent. 



T. Is the number of eyes the same in all ani- 

 mals ? 



A. The fly, the bee, and various insects, have 

 many eyes, or what is equivalent, set round on each 

 side of the head, though they are so united, as to re- 

 semble only two eyes at the first inspection. It re- 

 quires a microscope to see them, and the appearance 

 is extremely beautiful. Some insects, it is compu- 

 ted, have as many as several thousand eyes. 



T. What design of Providence do you here dis- 

 cover ? 



A. As these insects have no motion of the eye, 

 they would labor under an evident disadvantage, un- 

 less their organ of vision was a kind of multiplying 

 glass, looking in every quarter, and catching every 

 object. 



