NATURAL THEOLOGY. 



47 



B. It must be very perfect ; when we think how 

 quickly we can glance from one object to another,— 

 from surveying a star to threading a needle. Still, 

 one would hardly have thought there was occasion 

 for all this machinery to enable the eye to do what it 

 appears to do in such cases, without any exertion ; — 

 and yet we can feel there is some apparatus at work 

 about our eyes, which seems to strain when we try to 

 look at an object close up to our faces, or at a very 

 unusual distance. 



T. We have had a wonderful account of this or- 

 gan of the eye. But it is worthy a more minute de- 

 scription still. Its Divine Architect has introduced 

 contrivance upon contrivance, to render it the most 

 surprising telescope that was ever made. You may 

 go on with the description. 



A. In telescopes it is necessary, and the discove- 

 ry is a somewhat late one, that the glasses should not 

 all be of one Unci of glass. Though most persons 

 are not in the habit of observing it, for it requires a 

 close attention, yet it is a truth with regard to every 

 telescope or magnifying glass, let it be formed of what 

 kind of glass it may, that it produces a rainbow ap- 

 pearance, or variety of colors about the little bright 

 spot or image where the light is collected. The rea- 

 son is this. " Light consists of different colored parts, 

 as Sir Isaac Newton discovered, some of which are 

 sooner collected by the glass, or more quickly drawn 

 to a little circle or image, than the others ; the conse- 

 quence of which is, when we hold up a burning-glass 

 or a telescope glass to the sun, the lights of different 



