252 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



use has been made of the principles involved in the makers' uew photo- 

 graphic objectives, thereby gaining much in the size of the picture. 



Hovestadt, Prof. — Jenenser Glas und seine Verwendung in Wissenschalt 

 und Technik. (Jena Glass and its application in Science and Technique.) 



[The author discusses the construction and experience of telescope objectives 

 made of Jena glass.] 



Laboratorium et Museum, No. 1, TJOO, pp. 5-9 (2 iigs.). 



Fig. 5:;. 



Fig. 54. 



Fig. 55. 



(3) Illuminating and other Apparatus. 



Reichert's Large Projection Apparatus. — This apparatus (fig. 56) 

 is adapted for the strongest currents up to 60 and more amperes, and is 

 suitable for use in an Institute for experimental pathology. The case 

 is of strong oak lined with asbestos, and is fitted with ventilation and 

 diaphragm arrangements. The arc lamp is for hand regulation, and is 



Fig. 5G\ 



easily controlled from the outside in all its movements. The three- 

 lensed condenser system has* an aperture of 200 mm. The water- 

 chambar carries the Microscope with the iris diaphragm. The Micro- 

 scope is so constructed that objective and ocular, each of w T hich has its 

 own tube, can be easily exchanged for others, whilst the position of the 



