THE MICKOSCOPE 11 



stage, as shown, is of a mechanical type, and can be completely 

 revolved ; the screws for actuating it are conveniently placed, 

 whatever the position of the stage. The sub-stage condenser 

 has centreing-screws, with rack and pinion adjustment for 

 focussing. The mirror is carried on a swinging arm of sufficient 

 length to enable it to be brought well above the stage if 

 necessary ; and this will be found of use when opaque objects 

 are to be illuminated. The instrument has been in constant 

 use for widely varying classes of work, and has fulfilled every 

 requirement. 



Latterly, as an instrument was required which might be 

 available for metallurgical work and other opaque objects, as 

 well as for ordinary work, a Zeiss photo-micrographic stand 

 (Fig. 2) has also been adopted by the writer, and for the highest 

 and most critical work has proved in every way suitable. It has, 

 unfortunately, some of the disadvantages to which the Conti- 

 nental type of stand is subject, viz. lack of stability in the 

 horizontal position, and somewhat cramped sub-stage arrange- 

 ments ; but otherwise it is an instrument of the highest merit. 

 The fine adjustment is of very delicate construction and has 

 perfect motion, responding to the slightest touch and being 

 suitable for use with the highest powers used under the most 

 exacting conditions. The body- tube is very large to minimise 

 internal reflections and also to enable objectives of long focus 

 and large field to be used. The special mechanical stage, 

 designed for photo-micrographic work, has a very exact slow 

 motion in each direction, and in the larger type has great range of 

 movement ; it also allows of complete rotation. Either long- or 

 short-tube objectives may be used : in fact, the instrument is 

 designed so that it may be used for any purpose without 

 restriction. 



If the prospective purchaser of a microscope confines himself 

 to one of the makers whose instruments are mentioned below and 

 who are well-recognised manufacturers, he is not likely to be 

 other than satisfied. The descriptions are practically as given 

 in the makers' catalogues, but the writer has knowledge of, 

 and has personally tested, each of those described. 



Fig. 3 is that of an instrument well known among those 

 using large stands, which was manufactured at the suggestion 

 of Dr. H. van Heurck of Antwerp. The whole construction 



