matic corrections, but a considerably flatter and larger 

 angular field and longer working distance ; that is, the 

 distance between lens and object is greater and is an 

 important feature in higher powers, as it admits of 

 better illumination of the object and greater ease in 

 working. 



In all the better types of magnifiers the vulcanite 

 mountings are discarded for those made of metal, 

 especially German silver, although many are used of 

 pure silver and some even of gold. 



Reading Glass. When magnifying lenses reach 

 a diameter of 2 inches or more they are usually termed 

 Reading Glasses and are then provided with a "handle. 

 They are used to examine large objects or areas, where 

 a low magnification is sufficient, to enlarge small 

 printed matter, or to determine detail in engravings 

 and photographs. 



Bruecke Lens. This lens, named after its 

 inventor, is designed to give a longer working distance 

 between lens and object than can be obtained with 

 simple lenses of the same magnifying power and to 

 give an erect image at the same time, such qualities 

 being manifestly desirable for dissecting and similar 

 work. 



A combination of achromatic Jenses forms the 

 image which is viewed through an achromatic con- 



