MAGNIFICATION. 



Any student working with a microscope should be able to 

 determine the magnification of his instrument together with the 

 ocular micrometer ratio. 



Determination of Magnification by the Use of Wollaston's 

 Camera Lucida. 



Arrange the stage micrometer in position and focus on it until 

 the lines are clearly visible. Place the camera lucida on the ocular 

 and tilt the body of the microscope until the tube becomes horizon- 

 tal. Then raise the base of the instrument upon blocks, until the 

 distance from the ocular to the table is 25 c. m. Change the mirror 

 until the light is reflected through the tube of the microscope, after 

 which modify the quantity of light falling on the white paper, 

 which should be placed on the table beneath the ocular, until, by 

 looking through the camera lucida toward the table, the lines of 

 the stage micrometer will be seen on the paper below. Mark off 

 with a pencil the distance between the lines of the stage micrometer, 

 as reflected on the paper, and measure with a rule. To determine 

 the magnification, divide the size of the image by the size of the 

 object magnified, and the quotient will be the magnification of the 

 instrument, under the one condition. If the distance between the 

 lines on the micrometer is 1-10 m. m., and on the image 50 m. m., 

 then the magnification of the instrument in that condition is 

 50 -=-1-1 0=500. 



Determine the magnification with the several combinations of 

 oculars and objectives. 



The magnification can also be determined by the eye-piece 

 and stage micrometers. 



