246 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Fig. 55. 



Stringer's Focussing- Attachments to Photomicrographic Cameras.* 

 Among the various methods invented for making an effective connec- 

 tion between the Microscope fine adjustment and the long rod from the 

 end of the camera, the favourite has been an endless band passing round 



the milled head of the Microscope 

 and round a similar head attached 

 to the camera-rod. The arrange- 

 ment has, however, possessed the 

 drawback of not being readily- 

 detached from the Microscope. 

 E. B. Stringer's method of over- 

 coming this is shown in fig. 55, 

 which shows an adjustable roller 

 to keep the cord taut. The usual 

 milled head of the camera-rod, 

 around which the cord is passed, 

 is mounted on a frame, the lower 

 portion of which fits into a sleeve 

 A, and permits the rod on which 

 the milled head is carried to be 

 tilted forward, when the band is to encircle the fine adjustment head, or 

 to be removed ; the band is then made taut by setting the fitting vertical 

 again, a clamping screw B being provided for securing it. The long 

 camera-rod then engages with it. 



Simple Means of Producing Microphotographs with an ordinary 

 Camera.f — Mr. W. Forgan describes how, with a simple accessory 

 to an ordinary camera, small photographs of large objects may be ob- 

 tained. The camera should have a rigid front, and that portion carrying 

 the dark slide should be capable of being fixed rigidly in the position it 

 is to occupy while the photograph is being taken. The old form of box 

 camera would seem the very best for the purpose. The flange in the 

 camera front, used along with the accessory referred to, was that taking 

 the Boss portable Symmetrical and other lenses having the same size of 

 screw. Into this flange there was screwed a thick drawn tube, as large 

 as the aperture would allow, and on its outside was soldered a ring, 

 screwed to take the screw in the flange. The tube entered inside the 

 flange about 2 in. and was sprung at the end inside with cuts re- 

 sembling the letter T placed horizontally. The other end of this tube 

 or jacket was cut with an inside screw of 50 threads to the inch. 

 Another piece of telescope drawn tube was selected about 6 in. long 

 and made to slide easily in this jacket. A ring about £ in. broad 

 was soldered outside within an inch from the other end of this 

 last tube, and was also cut with a screw of 50 threads to the inch, so 

 that, when this tube was placed inside the jacket and turned round, 

 it could be made to approach or recede from the sensitive plate in the 

 dark slide by a very minute quantity. To enable this to be done easily 

 a large ring, knurled on the edge, was soldered on to the extreme outer 

 end of the tube. The effect of the whole arrangement was that the tube 

 could be rotated without the least apparent movement of the image on 



* Knowledge, Dec. 1901, p. 285 (1 fig.). 



t Proc. Scot. Micr. Soc, iii. (1901) pp. 79-82. 



