336 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
by means of gearing T. On the upper part of the main arm is a sleeve 
into which the condenser C, or other accessory, fits. On the under side 
of the same arm the iris-diaphragm is carried by the pivoted arm d, 
and can be swung out of position as shown on the left. For oblique 
illumination the diaphragm may be moved from side to side by the rack 
Fig. 26. Fig. 27. 
and pinion t. The whole apparatus is held in a central position by a pin, 
which projects from the under side of the stage, fitting into the hole a , 
when the apparatus is screwed upwards by the arrangement T. In cases 
where it is necessary to quickly change from convergent to parallel light, 
the condenser and diaphragm are hinged together, as is shown in figs. 26, 
27. Owing to the size of the apparatus, it 
can only be fitted to the larger stands. 
Coloured Illumination.* — Mr. J. 
Kheinberg describes a new form of “ sub- 
stage differential colour illuminator,” con- 
sisting of a box containing nineteen 
metal slides, which can be moved in or 
out independently of one another by means- 
of small handles. Each slide has two 
circular apertures, one of which is fitted 
with a colour disc or other stop. The 
kind of stop is indicated on the handle. 
When the slides are pushed in, only the 
blank apertures are in the path of the 
light, but when pulled out, one or other 
of the stops is brought into use. The 
stops for giving coloured backgrounds, 
and for illuminating the object with 
various stops, include a dark-ground stop, 
various colours, parti-coloured stops, 
stops for oblique light, several annuli, 
and a ground-glass stop. The various 
combinations of stops which can be 
brought into use are almost endless. 
Portable Microscope Lamp.t — Mr. 
W. Goodwin has designed a lamp made 
by Mr. Hinton (fig. 28). The metal chimney has two circular aper- 
tures 1 in. in diameter, one of which is glazed with signal green and the 
* Journ. Quekett Micr. Club, vi. (1897) pp. 346-7. f Tom. cit., p. 345 (1 fig.). 
Fig. 28. 
