OS 1 THE MICROSCOPE. 10? 



small area of support is best; for the former a stand with a flat 

 base resting over its whole surface on the table should be pre- 

 ferred. 



It is obvious that the causes of unsteadiness are either vibra- 

 tions transmitted from the floor, or movements caused by the 

 hand in performing the necessary manipulations and adjust- 

 ments. The first can never be stopped by weight, unless, 

 indeed, we make the stand so heavy that its weight will impart 

 rigidity to the table and floor, and this would require a good 

 deal more than fifteen pounds, or even twice that. For the 

 checking of vibrations transmitted from the floor, no device is 

 better than the stand or table described in a subsequent sec- 

 tion. So far as movements transmitted by the hand are con- 

 cerned, if a stand of three or four pounds will not resist them, 

 the observer should set himself about learning delicacy of 

 movement before he proceeds any further. 



All microscopes made in this country and in England are 

 now constructed so that the body may be inclined to any angle, 

 thus giving the power of using the microscope in any position 

 vertical, inclined or horizontal. The importance of this is 

 easily seen when we consider that on the one hand, when liquids 

 are to be examined, it is sometimes necessary, or at least desira- 

 ble to use the microscope in a vertical position, though this is 

 a very tiresome and inconvenient position, and one that is not 

 calculated to enable the observer to obtain the best possible re- 

 sults; and on the other, it is equally necessary that the body of 

 the microscope should be capable of assuming the horizon- 

 tal position when the camera lucida is to be employed for 

 making drawings, as will be hereafter explained. And yet 

 Frey actually gives the preference to microscopes that do not 

 incline, and which must always be used in a vertical position! 

 This, of course, necessitates the complicated and expensive ar- 

 rangement which he describes for adapting the camera lucida to 

 the vertical instrument, a singular instance of prejudice against 

 an obvious and successful improvement. 



The Stage. In every case, a large, roomy stage is of the 

 utmost importance. One great objection to most French in- 



