810 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Microscope with all the lenses convex and with reversed vision. The 
name microscopio was invented in Rome in 1625 by Giovanni Faber, 
a physician of S. Santita. 
(3) Illuminating: and other Apparatus. 
New Polarizer. * — Prof. S. P. Thompson read, at the British Associa- 
tion, a paper on “ A new Form of Polarizer.” He explained that owing 
to the great dearth of Iceland spar large Nicol prisms could not be 
obtained, and he therefore thought it expedient to devise some means 
of producing polarized light without its aid. The method proposed 
consists in reflecting the light from a black glass mirror, whose surface 
is covered with a plate of clear glass. In this way less light is lost 
than if black glass alone were used. The light from the lantern is 
reflected on the mirror by means of a total reflecting prism. After being 
polarized it is again turned back into its original axis by a second 
reflecting prism. This latter prism, however, must be very carefully 
annealed in order that the light may remain plane polarized. 
Microscope Mirror for Illumination by Reflected Light, f — Herr 
Gustav Selle has devised an ingenious method of illuminating the 
object. Immediately above the objective system is a concave mirror, 
which reflects the rays incident upon it 
Fig. 86. through an aperture in the side of the case 
of the objective in such a way that the 
external rays of the reflected cone acd 
(fig. 86), by passage through the objective, 
are refracted through the focus B to the 
further edge of the object b , while the in- 
ner rays are refracted parallel to the axis 
of the Microscope to the near side o. 
Electro-Microscope Slide for Testing 
the Antiseptic Power of Electricity. + — 
Dr. R. L. Watkins writes : — “ Fig. 87 
represents an instrument that I have de- 
vised for the purpose of ascertaining 
whether or not electricity will destroy 
the life of germs. It is the result of 
a number of experiments to confirm a 
belief I have long held, that electricity 
is an antiseptic and disinfectant. I also 
learned, while experimenting, that Apostrali had made the same 
claim. 
The instrument consists of a glass slide, in the centre of which is a 
sunk cell. Two grooves, each 3/4 in. long, run from this cell outward. 
Two brass pieces are fitted over the extremities of the slide in such a 
manner that the rounded points, the under surfaces of which are lined 
with platinum, will cover a portion of the grooves. These rounded 
points do not touch the glass, but are raised above the grooves about 
* English Mechanic, liv. (1891) p. 36. 
f Central-Ztg. f. Optik u. Mechanik, xii. (1891) p. 239. 
I Amcr. Mon. Micr. Journ., xii. (1891) p. 204. 
