1892.] MICKOSCOPICAL JOUENAL. 159 



ber is supported upon pillars, several feet above the body of a ver- 

 tically-placed stand with which it is connected by means of a bel- 

 lows-tube in the form of an inverted pyramid. An ingenious 

 reflecting arrangement enables the observer to examine most con- 

 veniently the image on the focusing plate above his head. An 

 extra bodv branches obliquely (after the Nachet foshion) from 

 the side of the ordinary one, and, by aid of a sliding reflecting 

 prism, is used for adjusting and examining the object until the 

 instant when a picture is required, at which time a sudden move- 

 ment of the prism allows a momentary flash of the microscopical 

 image upon the sensitive plate. The writer did not see this very 

 ingenious apparatus in operation ; but it is said by competent au-. 

 thority to work perfectly with electric light or direct sunlight. 



Superb photographic outfits were likewise displayed by E. 

 Hartnack ofPottsdam. the Carl Zeiss house of Jena, Carl Reichert 

 of Vienna, Ernest Leitz and W. & H. Seibert, both of Wetzlar ; 

 and scarcely inferior ones by other makers. Most of the makers 

 show two styles corresponding more or less to the first two Hart- 

 nack styles above mentioned ; one horizontal and elaborate, for 

 long distances, and a simpler An m inverted and vertical or in- 

 clined, for short distances of less than about a meter. 



Special photomicrographic stands, with bodies wide and short, 

 are shown by Zeiss, Reichert, Watson (the Van Heurck stand), 

 and others. Several maniffacturers also present special objectives, 

 or illuminators with heliostats, lime-lights or electric lanterns, 

 well adapted to this work. 



Photomicrographs in great number and variety and of every 

 degree of excellence were displayed upon the walls and crowded 

 in the cases not only of the main hall but also in a separate room 

 devoted to them. 



Thirteen prizes, of several different grades, were awarded in 

 this department. The first of these would certainly have been 

 voted to Dr. Van Heurck for his photographs of diatoms, on 

 account of the clearness and general excellence attained in treat- 

 ing subjects chosen for their extreme difficulty ; but, though not a 

 member of the jury of awards, his prominent connection with the 

 enterprise as the originator of the exposition and the leader of its 

 management led him, with very good taste, to decline to be 

 considered a competitor for any prize. 



One grand prize was awarded, to Dr. Giorgio Roster of 

 Florence, who exhibited four dozen extremely fine photographs 

 of natural-history objects, including diatoms, and of pathological 

 subjects. These were models of good photography and mount- 

 ing and of scholarh' labelling and arrangement. 



Four diplomas of honor followed : one to Prof. J. D. Cox of 

 Cincinnati and Mr. C. Houghton Gill of England, who conjointly 

 with Dr. Van Heurck exhibited a number of diatom photographs, 

 magnified from 500 to 1,500 times, displaying the structure of the 

 shells in a decisive manner by means of edge views of broken 



