346 General Notes. [ April, 
MICROSCOPY .! 
A New Fine Apjustment.—Mr. Ernst Gundlach, of Roches- 
ter, has introduced a device by means of which an extremely 
slow, fine adjustment can be obtained in addition to the ordinary 
coarse screw movement. It is described as follows: 
In working high powers, microscopists have felt the need of a 
finer adjustment than the ordinary micrometer-screw, which can- 
not be made much finer and still be durable enough. This 
need is now supplied by the combination of two screws which 
give a resultant motion equal to the difference in the threads em- 
ployed. One of these screws is a little coarser than the ordinary 
micrometer screw, and may be used alone as a fine adjustment, 
and a change can be made instantly from this to the finer motion. 
Either is given by one milled head located in the usual position 
of the fine adjustment screw-head on Gundlach’s microscopes, 
and the change is made by turning a smaller clamping screw 
having its head over thé former. By tightening the clamping 
screw, the adjustment is in order for the work of the combination ; 
by loosening, for that of the coarser screw only. As the thread 
of this is a little coarser than the ordinary micrometer screw, it 
alone gives a better motion for medium powers than the fine 
adjustment in common use, a second advantage of the invention. 
New Meruop or Dry Mountinc.—Mr. Frank French has con- 
tributed to the Postal Microscopical Club, a slide mounted in a 
style which promises to be useful for certain kinds of opaque 
objects which will bear occasional exposure to the dust and mots- 
ture of the air, and which are best viewed without, the interven- 
tion of a cover-glass, The slip is composed of cardboard cut LO”; 
3 X I inches, the required thickness in each case being attaine 
by building up a sufficient number of thicknesses, gummed to- 
gether. The centers are punched out as from the paper covers 
for glass slips; and the object is fastened at the bottom of the 
cell thus formed, either upon mica fastened at the bottom of the 
cell or upon a bottom card not punched like the rest. € 
object is covered by a rectangular brass sliding plate below the 
upper card, the card next below being cut away to receive it and 
to allow it room _to slide entirely away from sight when desired. 
A pin head is riveted and soldered into this brass plate, and pro- 
jects through the upper card, appearing near the right end of the 
finished mount, through a longitudinal slot that permits it to be 
pushed toward or from the other end of the slide, and thus to 
carry the brass plate over the object or away from it. The whole 
mount is finished by covering with paper in the old style. 
MovuntinG In Copat Varnisu.—]I find this varnish dries very 
rapidly if slightly heated, or even if placed ona previouly-warmed 
slide. I have many hundred slides of diatoms prepared in copal 
varnish, and my friend, Mr. Van Heurck, of Antwerp, who Wa> 
1 This department is edited by Dr. R. H. Ward, Troy, N. Y. 
