774 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
MICROSCOPY. 
a. Instruments, Accessories, &c.* 
Cl) Stands. 
Bachman n, O.— Unsere modernen Mikroskope und deren samtliche Hilfs- und 
Nebenapparate fur wissenschaftliche Forschungen. Ein Handbucli fur Histo- 
logen, Geologen, Mediziner, Pharmazeuten, Chemiker, Teclmiker, und Studier- 
ende. (Our modern Microscopes and their accessories for scientific inquiries. 
A handbook for histologists, geologists, medical men, pharmaceutical and other 
chemists, technical and general students.) Miinchen and Leipzig, 1890. 
Errera, L. — Microscope d’excursion de M. Amrhein. (Amrhein’s Travelling 
Microscope.) Bull. Soc. Beige de Micr ., XYI. (1890) p. 48. 
(2) Eye-pieces and Objectives. 
On Glass-smelting for Optical and other Scientific Purposes.f — 
Dr. Schott gives an account of the attempt, undertaken by himself and 
Prof. Abbe, to determine the mutual relations of optical effect and 
chemical composition for all possible amorphous compounds produced 
by solidification after fusion. It is now seven years since the idea of 
the work was first entertained. A year after the commencement of the 
undertaking sufficient data had been acquired to render it possible to 
predict that a systematic investigation of the question would lead to a 
considerable advance in practical optics. A building in Jena, suitable 
for carrying out the experimental work, was placed at the author’s 
disposal, and was provided with furnace, blast, &c. Here, during the 
next two and a half years, the chief practical work of the investigation 
was effected. What remained to be done was to render the results 
obtained of service to practical optics. In furtherance of this design 
it was decided to once more renew in Germany the production of optical 
glass. This industry had been brought to a high state of perfection by 
Fraunhofer, but was, after his death, allowed to languish. It was 
foreseen that a long and costly series of experiments would be required 
before success could be attained, and that little aid could be expected 
from foreign sources. A grant of 60,000 marks from the Prussian 
Government, supplied on patriotic as well as on scientific grounds, met 
the cost of the apparatus for the first two years. 
Fraunhofer had made experiments on the improvement of optical 
glass with much success. After his death, an English clergyman named 
Harcourt was the only one who undertook experiments of a similar 
kind, but the results obtained, although of interest, were of no practical 
utility. The following passage in a communication on the optical 
resources of the Microscope made by Prof. Abbe to the Exhibition of 
Scientific Apparatus in London in 1876, shows the condition of optical 
glass-smelting at that time : — 
“ It is not difficult to determine the fundamental grounds from which 
this want arises. The impossibility of getting rid of the chromatic 
differences of spherical aberration is dependent on the fact that, with 
* This subdivision contains (1) Stands; (2) Eye-pieces and Objectives; (3) Illu- 
minating and other Apparatus ; (4) Photomicrography ; (5) Microscopical Optics 
and Manipulation ; (6) Miscellaneous. 
t Central-Ztg. f. Optik u. Mech., x. (1889) pp. 221-3, 232-4. 
