1892.] THE MICKOSCOPE. 165 



and an archromatic objective by Beeldsnyder, an amateur in Hol- 

 land just lOO years ago (1791). This objective, exhibited by 

 Dr. A. W. Hubrecht, professor of zoology in the University of 

 Utrecht, is claimed to be the first one made, and is so well con- 

 structed as to give a very good image. It consists of two convex 

 lenses of crown-glass, with a biconcave of flint between them, and 

 appears to be the earliest known adaptation of the achromatic tel- 

 escope object-glass to the microscope, which was revived unsuc- 

 cessfullv at Modena bv Amici in 181 2, and successfullv modi- 

 fled and introduced at Paris in 1S23. 



A most interesting example of an ancient cabinet of slides was 

 a svstematic collection of 300 preparations (iSth centur}-) , in 

 ivory slips, four specimens in a row in each ; the objects were 

 mounted in holes bored through the slips, they and their covers 

 being held in place by wire rings sprung into the cell and upon 

 the cover. Interesting preparations by Andrew Pritchard were 

 also shown (London. 1825). 



Microscopes and Accessories. 



In this department the chief exhibitors were, naturally, the 

 manufacturers, and with only two notable exceptions they were 

 of the •'' continental " group. 



Among; the whole it was evident that one. the Carl Zeiss es- 

 tablishment at Jena, was easily pre-eminent, on the account of the 

 magnitude and variety of its exhibit, the high qualit}- of its work, 

 and the extent and importance of its contributions to the recent 

 development of the microscope, especially in inventing and in- 

 troducing new optical glasses of high refractive indices and in the 

 creation of the apochromatic objective. The exhibit included a 

 large varietv of the well-known Zeiss stands, with their different 

 classes and powers of oculars and objectives, and their outfit of 

 numerous and ingenious accessories ; also a special stand for pho- 

 tomicrography, a complete special photomicrographical apparatus 

 that is small and portable, and another of great size furnished 

 with a Schuckert electric lantern and the most elaborate appur- 

 tenances of various kinds. But the most interesting feature of their 

 exhibit was a demonstration of the construction of a large stand 

 and of an aprochromatic objective and a compensating ocular. 

 All the pieces entering into the construction of a No. i stand 

 were displaved spread out in a case, like a picture against the 

 wall, each piece being given in duplicate, once in the rough cast- 

 ing or section of tube or wire, and again in the finished form 

 ready for assembling into the completed instrument. In another 

 case were superb blocks of the new optical glasses of Drs. Abbe 

 and Schott of Jena, and of the fluorite of the Oltscheren Alp. 

 The different stages in the construction of an 8 mm. apochro- 



