678 SUMMARY OF CURRENT RESEARCHES RELATING TO 



(5) Microscopical Optics and Manipulation. 



Everett, J. D. — On the Resolving Power in the Microscope and Telescope 



Bep. British Assoc. Glasgow, 1901, p. 569. 

 Stbehl, K. — TTeber Luftschlieren und Zonenfehler. 



Zeit.f. Instrumenterik., XXII. (1902) p. 213. 

 Volkmann, W. — Ein neues Geradsichtprisma und ein neues Fliissigkeitsprisma. 



Ann. d. Phys. [4] VIII. (1902) p. 455. 



(6) Miscellaneous. 



The Microscope.*— Under this title, A. S. Percival contributes to the 

 English Mechanic a brief but clear and interesting explanation of the 

 peculiarities of lens structure concerning the Microscope. He deals, 

 inter alia, with magnification, spherical aberration, chromatic aberration, 

 apochromatic objectives, size, brightness and flatness of image, and 

 Huyghenian eye-pieces. 



Wave-length Tables of the Spectra of the Elements and Compounds. 



Bep. Com. Brit. Assoc, 72nd Meeting, Belfast, 1902. 

 London (J. Murray) 1903, pp. 137-74. 



B. Technique. f 

 CD Collecting: Objects, including- Culture Processes. 



New Economical Thermostat of Simple and Light Construction.^ 

 C. Tonzig describes a thermostat which can be easily and cheaply made 

 by an ordinary joiner and tinsmith, and which is well adapted for a 

 temperature of 20° or 22° C. It measures 40 X 60 x 75 cm., and is 

 made of wood, 2 cm. thick. Through the middle of the chamber a 

 cylindrical tube of zinc passes vertically. This cylinder extends 5 cm. 

 above the roof of the chamber, and below the floor it expands in the 

 form of a cone, which is closed at the bottom by a plate of copper, this 

 part being exposed to the flame when the thermostat is in use, and the 

 cylinder full of water. The upper end of the cylinder has in it two 

 openings, one for the thermo-regulator and another for a thermometer, to 

 gauge the temperature of the contained water. In the roof of the 

 chamber near one of the sides is another opening for a thermometer, to 

 gauge the incubator temperature. The diameter of the cylinder is 

 7*5 cm., that of the base of the cone 18 cm., its capacity, therefore, 

 is about 4900 ccm. The author uses a Soxhlet's thermo-regulator, but 

 when gas is not available, a constant temperature can be maintained by 

 the use of one or more night-lights in oil. The air of the chamber is 

 warmed by convection of heat given out from the cylinder. The tem- 

 perature was found by experiment to be uniform in all parts of the 

 upper part of the thermostat. In the lower part the temperature was a 



* English Mechanic, lxxvi. (1903) pp. 430-3 (15 figs.). 



t This subdivision contains (1) Collecting Objects, including Culture Pro- 

 cesses; (2) Preparing Objects ; (3) Cutting, including Imbedding and Microtomes; 

 (4) Staining and Injecting ; (5) Mounting, including slides, preservative fluids, &c. ; 

 (6) Miscellaneous 



X Centralbl. Bakt., 2 te Abt., x. (1903) pp. 531-4 (1 fig.). 



