The Microscope. 81 



three dollars, and I would not change it for a Louis XIV. or a 

 Chippendale. All that is needed is that it shall be solid and 

 firm, with an abundance of top space, and a drawer or two to 

 hold the many " traps " and " dodges " that soon accumulate. 



Seated before the stand, incline it at a convenient angle, the 

 stage, the mirror, that is, the front of the microscojDe, of course 

 being turned from you. When inclining the instrument, do so 

 if possible by means of the arm, at any rate do nothing to bring 

 a strain on the coarse or fine adjustment. All the least costly 

 stands will remain in an inclined position, held there by the 

 friction within the joint at the top of the pillar ; in first class 

 instruments the trunnions carry tightening or binding screws, 

 so that the wear that sooner or later becomes noticeable in the 

 former can be taken up in the latter. 



With the eye-piece in place, and the body inclined, attach the 

 objective. To do this, rack up the body until there is no danger 

 that the front of the lens will come in contact with the stage. Un- 

 screw the top of the brass box containing the objective and tip 

 the latter out into the palm of the left hand, supporting it with 

 the fingers. Take it up with the right hand, and turning the 

 screv/ end upward, screw it to the lower end of the body tube. 

 It is unnecessary to caution the reader in regard to crossing the 

 threads of the screws. If that be done and the objective wedged 

 into the nose-piece, the owner of that stand may have a sad ex- 

 perience. Mr Wm. Wales relates an instance of this kind where 

 the objective could not be removed by hand, so the wise owner 

 used a heavy pair of gas-fitter's pliers, and succeeded in damag- 

 ing the instrument to the amount of forty-five dollars, pulling 

 out the entire fine adjustment which in this case was on the 

 lower end of the body. It is often useful to rotate the objective 

 backward for a short distance, until the threads are felt to slip 

 into place, when the lens may then be screwed home by gentle 

 forward turns. If it does not move easily and smoothly, some- 

 thing is wrong, and no force should be applied, but the objective 

 must be removed and the difiiiculty discovered and corrected. 



If the microscope is to be used by day-light a position near a 

 north window is the best, as the light from the northern sky is 

 the most uniform. A white cloud illuminated by the sun is the 

 most desirable light by day, but it can seldom be obtained. 

 Most microscopists have some favorite position before the win- 



