1892.] THE MICKOSCOPE. 171 



placed horizontally in connection with this ; but it has also an 

 extra body branching vertically from the main body, just behind 

 the objective, and supplied with a sliding prism which serves, 

 when racked down, to totally reflect the light from the objective 

 up through the vertical tube which is used for observation while 

 adjusting the object and the illumination, and when racked up 

 permits the same pencils to pass horizontally directly to the sen- 

 sitive plate at the far end of the bellows. His •• petite apparatus " 

 designed for elementary work is very simple, the dark chamber 

 being a plain box supported over the ocular end of an ordinary 

 microscope standing either vertically or inclined. This box, with 

 its sensitive plate at the top, can be clamped at various heights 

 upon a pair of parallel supporting bars, the latter being jointed at 

 the level of the microscope stage, so that they may be maintained 

 parallel with the body at anv desired inclination. His mammoth 

 style of " inverted microscope" (which will be remembered as a 

 conspicuous feature of his exhibit at our Centennial exhibition at 

 Philadelphia in 1876) is also fitted with an inverted dark chamber 

 which is supported upon the top of the inclined tube, and which, 

 with such a support, has naturally the advantage of extreme stead- 

 iness. But Nachet's most unique device is the apparatus for in- 

 stantaneous photography of living objects, as infusoria, etc. This 

 is an elaborate and finely-built atiair. The inverted dark cham- 

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

 tically-placed stand w^ith which it is connected by means of a bel- 

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

 reflectinof arrangement enables the observer to examine most con- 

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

 extra bod v branches obliquely (after the Nachet fashion) 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 m^omentary 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. 



vSuperb photographic outfits were likew^ise 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 scarce!}' 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 form 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 manufacturers also present special objectives. 



