PRACTICAL EXERCISES 



1105 



1IL v*******^* 



in LII<= r' fitmre showing a number 



^ . . 



marked, 

 convenien 



the Ophthalwometer. - A 

 P^V/^nwninFigs. 476 







Snined; H. ^S'tafe of ?SS 



ated discs on w hich . r 7" ri us me ri 

 ture of the 



Hind. 



until ^ XerTnd equally distinct 

 close together an a 4 | 4?7( d) 



Rotate the o ^ r er \^ n lines of the 

 until ^ long c ^er^an ne ^^ 



illuminated mires. or spu rs ol 1 the ^ a | nd the adjus t- 



But if the e^ is a ff^ r ' e made to coincide so '^^ bet ween 

 rotating A, the / h _ d the graduation is rea ,^ er ^e between the two 



a?e t oSry astigmatism. 



