334 SUMMARY OF CURRENT RESEARCHES RELATING TO 
Z>, which is fitted with an iris-diaphragm, and is reflected by a mirror 
at a on to the object. The instrument is especially designed for 
studying the structure of etched and fractured surfaces of metals and 
alloys; it will also be useful for observing the surface characters of 
minerals, rocks, &c. 
(3) Illuminating- and other Apparatus. 
Improved Illuminating Apparatus.* — Herr C. Eeichert describes 
an improved form of the Abbe substage illuminating apparatus, of 
* Zeitschr. f. angew. Mikr., iii. (1897) pp. 33-5 (4 figs.). Cf. this Journal, 1896, 
p. 373. 
