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SUMMARY OF CURRENT RESEARCHES RELATING TO 
lamp-rest which slides on cleats attached to tho corner braces, and has 
an upright for concave reflector when desired. H, sliding carrier for 
camera, with tongued arms of sufficient width to bring the photographic 
lens collar precisely over the microscopic tube when centered on either 
base. I, set-screw to retain it in position, and J, milled head of pinion 
by which it is racked down to attach camera K to eye-piece of Micro- 
scope. This light-tight connection is made with one-half of a child’s 
rubber ball, perforated in centre to fit neck of eye-piece, and of sufficient 
size to fill the collar of the photographic lens. Fig. 82 illustrates use 
of the stand in copying enlarging, and reducing, and requires but little 
explanation. N, N, base-board, 5x1 in., 4 ft. long, grooved on edges 
to receive tongues on arms of camera-carrier. It is hinged to apex of 
wedge-shaped block O, the gudgeon of which fits snugly into the hole 
in centre of supplement base ; S, telescopic boxes ; R R, slot passing 
beneath the camera-carrier, with upright for carrying the picture to be 
copied, the distance respectively between the lens and the picture, and 
the lens and ground-glass, being regulated by the operator without 
leaving his position at the focusing screen, so that all copies may be 
brought to a uniform size, as for lantern slides, without regard to the 
size of the original. Removing the telescopic boxes and slot, we have 
a convenient camera stand for inside use, the lateral movements being 
secured by the gudgeon attachment, and the vertical by the screw 
brace P. If used ordinarily as a Microscope stand the instruments 
are always in line and position for photomicrography.” 
Beck’s Bacteriological “Star” Microscope. — This Microscope, 
which was exhibited at the October meeting, is made in two forms, one 
with a sliding and the other with a rackwork coarse-adjustment. The 
fine-adjustment to both forms is that known as the micrometer screw. 
It is also provided with an inclining joint, a draw-tube, and a swinging 
double mirror. The special feature of the instrument is the movement 
of the substage ; this is done by a milled head at the right-hand side 
of the instrument, by the revolution of which the substage is raised or 
lowered. When it has been moved to its lowest position a further 
turn of the milled head turns the substage out of position to the right- 
hand side of the instrument. The substage is fitted with an Abbe con- 
denser and iris diaphragm. 
Giant Projection Microscope.* — In the Optical Institute of Franz 
Poeller, in Munich, an enormous projection Microscope is now being 
constructed for the “ World’s Fair ” at Chicago. Electricity plays a 
great role in this instrument. In the first place it supplies and regu- 
lates the source of light which is mounted in the focus of a parabolic 
aluminium reflector, and has an intensity of 11,000 candles. By means 
of an ingenious piece of mechanism, it also maintains the centering of 
the quadruple condenser and the illuminating system. It also serves 
to control exactly the distance of the carbon points. For this purpose 
the arc forms part of a shunt whose intensity is measured by a galvano- 
meter, by the movement of the needle of which the distance of the 
carbon points can be read to the tenth of a millimetre. The most im- 
portant innovation, however, is the arrangement for cooling the instru- 
* Central-Ztg. f. Optik u. Mechanik, xii. (1891) p. 178. 
