94 



Journal of Applied Microscopy. 



it at a pressure which is measured by 

 the weight of the float, plus or minus 

 the resistance due to friction. If the 

 apparatus is well made, the resistance 

 amounts to only 1 or 2 mm. on the 

 manometer, and it is only exerted during 

 the changes of position of the float. If 

 the pressure in the gas pipes falls to 

 that in the apparatus, the float falls to 

 the bottom, opening the valve to its 

 fullest capacity, and allowing gas to 

 flow through unhindered. 



Thanks are expressed to Mr. J. T. 

 Faig for the drawings herewith given, 

 and to Professors P. C. Freer and F. G. 

 Novy for assistance rendered in various 

 ways. 



Paul Mureill. 



University of Michigan, Ann Arbor, Mich. 



A Practical Photo - Micrographic 

 Camera. 



The desire among photo-micrographers 

 to go to the extreme limit of enlarge- 

 ment, and the complicated and expen- 

 sive apparatus required to obtain 

 these results, has led the majority 

 of microscopists to believe that no 



Fig. 1. 



good work can be done except with an 

 equipment of a very expensive character 

 and with an undue expenditure of time 

 and labor. The result has been that this 

 highly valuable aid to the investigator 

 and instructor has not been employed to 

 the extent which its usefulness would 

 warrant. The form of camera illus- 

 trated in the accompanying figures has 

 been designed for working microscopists, 

 i. e., biologists, pathologists, and others 

 to whom the microscope is a necessity. 

 The object aimed at is to give as much 

 magnification as is compatible with the 

 requisite compactness and stability in 

 order to make the apparatus convenient 

 and rapid to use. In order to secure 

 stability the base is a solid iron plate 

 upon which the microscope rests (any 

 microscope may be used with this 

 camera), and above which the camera 

 bellows is supported on two solid steel 

 rods three-quarters inch in diameter, 

 and thirty inches long. The bellows has 

 an extension of eighteen inches and is 

 supported at either end on cherry 

 frames. 



The ground glass is provided with a 

 central transparent area, formed by 

 cementing a cover glass upon the ground 

 glass, and permits the accurate focusing 

 of the most delicate detail. In order to 

 make it possible to use the camera in 

 any position with equal facility, the 

 vertical rods supporting the bellows are 

 attached to very heavy metal arms 

 which are immovably fixed to a horizon- 

 tal axis, thus permitting the camera to 

 be tilted to any angle from vertical to 

 horizontal. It is fixed at the desired 

 angle by means of the two heavy hand- 

 clamps shown in the figure, the construc- 

 tion being such as to secure perfect rig- 

 idity. The camera is made for 4X5 

 plates, but lantern-slide sizes can be 

 used by means of kits. 



In use, the camera is placed in a ver- 

 tical position and the microscope ad- 

 justed on the base so that its tube will 

 coincide with the opening in the front 

 of the camera. The connection between 

 microscope and camera is made light 

 tight by means of a double chamber 

 which permits considerable vertical mo- 

 tion of the tube of the microscope with- 

 out readjustment. In order to make this 

 camera usable with any sized microscope 

 and with the camera in any position, 

 the upper and lower frames supporting 

 the bellows are laterally 

 adjustable, and gradua- 

 tions indicate when both 

 are centered. A jointed 

 telescoping rod is at- 

 tached to the upper end 

 of the camera to act as 

 a support, giving perfect 

 steadiness when in a 



