ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
Ill 
MICROSCOPY. 
a. Instruments, Accessories, &c.* 
(1) Stands. 
Practical Remarks on Microscope Construction.! — Dr. H. E. Hil- 
debrand makes some practical remarks on Microscope construction : — 
I. The Continental stand and its fine-adjustment. The author points 
out that in teaching establishments where as many as two hundred 
Microscopes may be used by a large number of pupils, the weak points 
of the stand are soon brought to light. There are certain parts of the 
Microscope which become injured with great regularity — viz. the micro- 
meter-screw has become unsteady; the prism has suffered bending or 
rotation ; the prism flauge, or the hinge-block under the object-stage, 
have loosened their connection with the stage-plate. In this connection 
the author discusses the question as to where and how the Continental 
stand should be held in moving it from one place to another. The most 
convenient method, and the one consequently most often adopted by 
scholars, is to use the prism-socket as handle. The effect of this is to 
subject the micrometer-screw, the prism, as well as its fastening, to con- 
siderable pressure, torsion, bending, rotation, and displacement ; and 
when once a defect is started it magnifies itself with astonishing rapidity. 
Although this method of manipulation must therefore be reckoned as 
faulty, yet it appears on the other side that it would be highly desirable 
that the prism-socket should be suitable as the handle to the instrument, 
not only in its position but also in its construction. To render this 
possible the socket should be rigidly connected with the object-stage, 
and the prism with the body-tube. 
There are two ways by which this could be effected. One is to pass 
the spindle of the micrometer-screw through a boring in the prism and 
fix it at the bottom of the socket. The screw-head in the old position 
acts then on the prism, which is pressed upwards by a spring. This 
method, however, was rejected, since it appeared that there was not 
sufficient guarantee for the absolutely correct motion of the prism. The 
second way of attaining the object in view is to throw out from the 
socket connected with the object-stage a projecting piece over the upper 
end of the prism, and from this piece to control the ascending prism by 
means of the micrometer-screw. The projecting piece rises from the 
upper face of the socket with three arms a a a, passes through openings 
ooo in the part p of the tube-support which surrounds the upper part of 
the prism, and widens itself above the end of the prism into a round 
disc s, through the middle of which the micrometer-screw passes 
(figs. 1, 2, 9*), The figures show how hinge-block, object-stage, and 
support, in which the prism-socket is screwed, are formed out of one 
piece of cast iron. A chamber at the lower end of the socket serves to 
receive the spiral spring for maintaining a central pressure on the 
* This subdivision contains (1) Stands ; (2) Eye-pieces and Objectives ; (3) Illu- 
minating and other Apparatus; (4) Photomicrography; (5) Microscopical Optics 
and Manipulation ; (6) Miscellaneous. 
f Zeitschr. f. wiss. Mikr., xii (1895) pp. 145-54. 
