\_CH. I 



MICROSCOPE AND ACCESSORIES 



3' 



With two fingers of the right hand take hold of the milled ring 

 near the back or upper end of the objective and screw it into the 

 tube of the microscope or nose piece. Reverse this operation for 

 removing the objective. By following this method the danger of 

 dropping the objective will be avoided. 



§ 55. Putting an Ocular in Position and Removing it. — 

 Elevate the body of the microscope with the coarse adjustment so 

 that the objective will be 2 cm. or more from the object — grasp the 

 ocular by the milled ring next the eye-lens (Fig. 37,) and the 

 coarse adjustment or the tube of the microscope and gently force 

 the ocular into position. In removing the ocular, reverse the opera- 

 tion. If the above precautions are not taken, and the oculars fit 



Fig. 40. Triple nose- 

 piece or revolver for 

 quickly changing objec- 

 tives. 



This covered or dust 



proof form was original- 

 ly devised by Winkel of 

 Goettingen; it is now 



furnished by nearly all 

 microscope makers. (Cut 

 loaned by Voilgtldnder 

 & Soh n, A. G. 



Microscope makers usually construct the double or triple nose-pieces and 

 the length of the objective mounting so thai in turning from one objective to 

 another all will be approximately in focus. The objectives are then said to be 

 par-focal. 



snugly, there is danger in inserting them of forcing the tube of the 

 microscope downward and the objective upon the object. 



§ 56. Putting an Object Under the Microscope. — This is 

 so placing an object under the simple microscope, or on the stage of 

 the compound microscope, that it will be in the field of view when 

 the microscope is in focus (§ 57). 



With low powers, it is not difficult to get an object under the 

 microscope. The difficulty increases, however, with the power of 

 the microscope and the smallness of the object. It is usually neces- 

 sary to move the object in various directions while looking into the 

 microscope, in order to get it into the field. Time is usually saved 



