PLAT3 



, 57- 



Fig. 53. 



Fig. 59. 



Polari/er. placed beneath 

 the obiect p 



r'lfe'. 60. 



ser placed above 

 the object, p. '." 



Fig. 61. 



Collins 1 n-?-r iradnatinA diaphragm, p 



i - s reflector 



for drawing, p. 27. 



iig. 63. 



ICC -ftlS i : 



2rf thf 1 1 



ICC 'ttLS 11. I'M 



i hunaredths and tliousandths magnified in different 

 degrees- p. 37. 



Fig. 65. 



Simple finder, designed by Mr. Wright, p. -1 :. 



Fig 67. 



A portion of Maltwood's finder, as 

 seen in the microscope, p. 43. 



. ! 66. 



1OOO 



Lines separated by 

 yJ-- of an incb. 

 magnified 215 dia- 

 meters, with objects 

 magnified in tne 

 same degree, p. 37 



Mode of ascertaining the magnifying power of an object-glass. 

 a lOOOtha of an inch x 200. b. IKOH SCALE DIVIDED INTO TENTHS. 

 c, lOOOths of an inch x 130. d. IPOths of an inch X 40 Each 

 magnified 1000th of an inch covers two. tenths, or one-fifth of 

 an inch, therefore the. glass magnifies 200 times, for Y^^ x 

 200 = T S 5 or -|. of an inch. Each 100th of an inch covers four- 

 tenths of an inch, therefore the glass magnifies 40 times, for 



Til- P- 38 ' 



Instrument for scratching a 



circular line on the thin 



glass, to show the position 



.of an object, p. 41. 



[To face page 



