130 THE MICROSCOPE. [June, 



instrument may be inclined to the most comfortable point, and 

 when so is more comfortable than the upright position. 



The joint for inclination of arm is generally conceded to bean 

 advantage. While it may be the case that many of the upright 

 instruments are in use in Europe, there are very few used in this 

 countrv. and the preponderance of instruments shown in cata- 

 logues of foreign makers would indicate the same tendency. 



Almost all instruments for reliable work are provided with fine 

 and coarse adjustment. They are both necessary, the only ques- 

 tion being whether the latter shall be by the sliding tube or rack 

 and pinion. The former, while perhaps having the advantage 

 of admitting a more speedy change of objectives, has a decided 

 disadvantage in the hands of the student in endangering objectives 

 and preparations. Further than this, it is almost impossible for 

 the maker to centre the nose-piece with the tube, so that a change 

 of objectives usually loses an object out of the field, and requires 

 that it be looked for anew with each change. In the rack and 

 pinion the nose-piece has an unvarying relation to the tube, and is 

 not liable to this difficulty, and ofters a steady and agreeable ad- 

 justment. The advantages of the rack and pinion seem to be 

 generally appreciated in this country, for there are few instru- 

 ments sold and used \vithout it. 



Whether an instrument shall be of japanned iron or lacquered 

 brass is probably largely determined by the amount of money to 

 be expended. As far as the intrinsic suitability of the metals is 

 concerned, there is no difi'erence. Brass, however, ofters the 

 maker a better opportunity for displaying his mechanical skill, 

 and while it is no doubt true that many highly finished instru- 

 ments are of poor workmanship in their working parts, it is also 

 a fact that a well-made instrument is always nicely finished. 



The size of instrument is worthy of consideration. If an in- 

 strument is to remain stationary in a practitioner's office or labora- 

 tory, it may be large without being cumbersome. If, however, 

 it is intended to be carried about, it should be of the smaller and 

 more contracted style. 



Another important consideration is the space between the stage 

 and base or table. While it is advisable to have the stage low on 

 account of convenience in manipulating a slide, there should still 

 be sufficient space for the convenient attachment of substage ac- 

 cessories. As a rule, the American pattern of instruments pro- 

 vides more room between the stage and base on the lower side, 

 and between the stage and tube on the upper, than do the Conti- 

 nental. As stated previously, a variety of stages are offered on 

 instruments of similar construction. The plain flat stage, while 

 preferred to some, offers no advantages over the ordinary round 

 one, unless specially made for examining specimens on slides 

 larger than the standard 3 by i inch. Some claim advantages 



