NATURAL THEOLOGY. 63 



it does not follow, there should be a curious mechan- 

 ism by which it can adjust its glasses, to enjoy the 

 advantage of a microscope and a telescope at the 

 same time ; it does not follow, there should be the 

 contrivance of a perforated curtain, by which the 

 quantity of light admitted or excluded is tempered to 

 the delicate sensibility of the eye ; it does not fol- 

 low, that the glasses should be of different substances, 

 or so constructed as to contain the highest improve- 

 ment of the mbdern telescope, in regard to prevent- 

 ing a certain rainbow appearance, which would ob- 

 scure the sight ; it does not follow, there must be an 

 increasing consistency of the principal glass, from the 

 edge to the middle, remedying another inconvenience 

 to which all the telescope glasses of the same form 

 that ever were or can be made are unavoidably sub- 

 ject ; it does not follow, that the principal glass must 

 also lessen its consistency from the centre to the 

 sides, so as to agree and make, as it were, one sub- 

 stance with the glasses between which it is situated, 

 thus avoiding another difficulty which in every other 

 telescope, of a similar nature, is perfectly incurable ; 

 it does not follow, that the nerve of the eye, which 

 receives the image, should enter a little out of the 

 centre towards the nose, so as to prevent any image 

 from being lost in both eyes at the same time ; and, 

 when we have a perfect eye, it does not follow, it 

 should be so well protected, and preserved so con- 

 stantly bright and fit for use ; that it should be lodged 

 in a bony cavern for its more perfect protection from 

 all outward violence, with a soft, flexible veil hang- 



