294 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



bellows and its frames run arc made to slide into one another, and when 

 the camera is completely closed tlicy can be placed under the base on 

 which the Microscope stands, so as to be out of the way. The Microscope 

 used for photomicrograph ic work is fixed to a slide which moves between 

 guides on the base in such a way that the tube is horizontal, and is 

 directed to the centre of the camera, the optic axis of the Microscope 

 passing through the centre of the sensitivo plate. The Microscope may 

 at any time be removed, to be used for other purposes, and can be rapidly 

 and easily clamped in the right 2'osition. 



To adjust an object, the front of the camera which is nearest to the 

 Microscope, together with the partly conical tube of 30 cm. length, which 



Fig. 56. 



is provided with internal diaphragms, is drawn out, the Microscope is 

 pushed in on its slide until its end approaches the aperture of the conical 

 tube, the lamp or other source of light is then adjusted, and the object 

 is adjusted in accordance with the directions of Dr. Neuhaus, which are 

 supplied with the camera, the camera front is replaced and clamped, and 

 the light-proof connection between the camera and Microscope is fixed 

 in its place. 



The fine-adjustment is effected by a curved forked clamp made of 

 watch spring, the two ends of which take into the milling of the micro- 

 meter screw ; two strings are attached to the clamp, and passing over 

 pulleys on the right and left hand, traverse the whole length of the 

 camera, and are fastened to a wooden rod ; the strings can be rolled or 

 unrolled upon the rod so that the latter always hangs in front of the 

 camera. When the camera is drawn out the string is lengthened by 

 unrolling it. By pulling upon the one string or the other the micro- 

 meter screw is made to turn to the left or right. In this way the fine- 

 adjustment is made without any inconvenient connecting rods, and can 

 be effected directly by one hand, while the other is engaged with the 

 focusing lens; the motion obtained by the clamp on the micrometer 

 screw is, it is claimed, quite fine enough to secure the complete sharp- 

 ness of the image. 



The plates which can be used are 13 x 21 cm., or half that size. 

 With the arrangement of the source of light, illuminating lens, and 

 Microscope described, impressions may, it is said, be taken of Bacteria 

 X 1000 with an ordinary petroleum lamp and an exposure of a few 

 minutes. With direct sunlight an exposure of a few seconds is enough 

 even with the highest powers. 



