g2 Microscopical Essays, 



to AB; that is, if we would fee the object tinder an angle as 

 large as FEG, or would make it appear the fame length that an 

 object as long as F G would appear, it may be done by coming 

 nearer to the object. For the apparent diameter is as the dift ance 

 inverfely; therefore, if CD is as much lefs than C E, as FG is 

 greater than AB, by bringing the eye nearer to the object in the 

 proportion of CD to ED, the apparent diameter will be mag- 

 nified in the proportion of F G to AB ; fo that the object AB, 

 to the eye at D, will appear as long as an object. F G would ap- 

 pear to the eye at E. In the fame manner, 'we might (hew, that 

 the apparent diameter of an object, when feen by the naked eye, 

 may be infinite. For fmce the apparent diameter is reciprocally 

 as the dif lance of the eye, when the diflance of the eye is nothing, 

 or when the eye is clofe to the object at C, the apparent diameter 

 will be the reciprocal of nothing, or infinite. 



There is, however, one great inconvenience in thus magnify-, 

 ing an object, without the help of glafles, by placing the eye 

 nearer to it. The inconvenience is, that we cannot fee an object 

 diftinctly, unlefs the eye is about five or fix inches from it % there- 

 fore, if we bring it nearer to our eye than five or fix inches, how- 

 ever it may be magnified, it will be feen confufedly. Upon this 

 account, the greateft apparent magnitude of an object that we 

 are ufed to, is the apparent magnitude, when the eye is about five 

 or fix inches from it : and we never place an object much within 

 .that diflance; becaufe, though it might be magnified by this 

 means, yet the confufion would prevent our deriving any advan- 

 tage from feeing it fo large. The fize of an object feems extra- 

 ordinary, when viewed through a convex lens ; not becaufe it is 

 impoffible to make it appear of the fame fize to the naked eye, 

 4 but 



