WITH THE MICROSCOPE. 235 



and gaslight he was dissatisfied, yet the succession of electric 

 sparks (about 100), from a small Leyden jar of 30 inches coated 

 surface, gave actinic rays of sufficient intensity to produce a good 

 impression on a sensitive collodion plate. Mr. Wenham, how- 

 ever, upon the whole gave the preference to sunlight. Mr. Hewlett 

 also used sunlight, and condensed it from a plane mirror or solar 

 reflector by a six-inch double convex lens. The Rev. Mr. Kingsley 

 with a special apparatus used the hydro-oxygen light and a screen 

 of esculine. Mr. Bockett, in 1862, tried diffused daylight, allow- 

 ing in some cases an exposure of from four to eight minutes. 

 Dr. Maddox, in 1864, succeeded, by using the brilliant light emitted 

 on the combustion of magnesium wire (i ^ inch) held in the flame 

 of a small spirit lamp, and condensed by an ordinary condensing 

 lens. Mr.. Durham also now uses gas and daylight illumination very 

 successfully. 



APPARATUS. 



Two modes of arranging the apparatus have been devised,- In 

 the first, the ordinary compound microscope is placed horizontally 

 in connection with an ordinary camera by inserting the eye-piece 

 end (the eye-piece being removed) into the brass setting of a well- 

 made portrait combination (the lenses having been removed), and 

 the aperture around the body of the microscope perfectly closed by 

 any simple method, as a card cap or cone of black cloth or velvet 

 attached to both. 



In the second, the ordinary microscope is dispensed with, the 

 objective, stage, and mirror being adapted to the front of a well-made 

 camera in the place of the usual combination ; proper arrangements 

 being made for holding the object, supporting the mirror, and adjust- 

 ing the different special parts. The pocket microscope described in 

 p. 1 4, may be adapted to the camera. 



325. Camera with Objcct-Glasses and Stage adapted to it. The 

 apparatus used by Mr. Delves was brought before the public by 

 Mr. Highley, and very much perfected by him. This form of 

 apparatus attracted considerable attention at the late International 

 Exhibition. M. Duboscq also exhibited this arrangement. It seems 

 to meet most requirements for moderate distances, but demands 

 especial outlay. Mr. Highley has lately introduced further improve- 

 ments, which make his apparatus still more perfect See pi. LI, fig. 



329- 



326. Mr. Wenham's Arrangements without a Camera. Mr. 



