SOMETHING ABOUT AMERICAN STANDS, ETC. 25 



Many of the first-class stands (so called) are fitted 

 with sub-stages, provided with rack and pinion, and 

 centering screws. In the latter models these accessories 

 can be completely removed, leaving the entire instru- 

 ment below the stage clear and unobstructed. Beyond 

 the cost which these appliances incur, I see no particu- 

 lar objection to their presence ; but the novice is in- 

 lormed that they are by no means a necessary adjunct, 

 and that their duties can be performed by simple and 

 less costly contrivances. 



Stands have lately been introduced with short tubes, 

 but capable, by means of an interior draw, of being 

 <lrawn out to the standard length of ten inches. This 



O 



is an improvement on the short tube of the German 

 school, and one of real value. The daily worker will 

 find the short tube a great convenience when working 

 over wet preparations, or dealing with reagents. Under 

 these circumstances, to work quickly one must needs 

 keep the stage horizontal and the tube vertical. It is 

 true that we can compensate, in a measure, in using the 

 standard lengths by working with a lower table ; but 

 in this case the observer cannot have his instrument so 

 well under control, and he is further compelled to re- 

 sort to some out-of-the-way contrivance by way of get- 

 ting rests for the elbows. 



In the selection of a stand, I advise strongly that it 

 be fitted with a concentric rotating stage ; and should 

 the res angusta domi present no obstacle, let the stage 

 be a good one, divided to degrees, capable of an entire 

 revolution, and furnished with an object-carrier. The 



