ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



453 



Fig, 



In order to examine and focus this image there is at the lower part of 

 the camera a small shutter, behind which is a hole filled in with opaque 

 glass. At the bottom of the 

 camera-box is a mirror, which 

 by means of a lever can be 

 inclined at an angle of 45°, 

 and the image thereby thrown 

 on the small plate of opaque 

 glass. It is then focused in 

 the usual manner. 



If considerable amplifica- 

 tion of the image and high 

 magnification be necessary, 

 the focusing must be done 

 directly on the large opaque 

 screen. For this purpose a 

 special arrangement is neces- 

 sary, in order to be able to 

 work the fine-adjustment. The 

 milled head of the fine-adjust- 

 ment is replaced by a toothed 

 one. The stand which sup- 

 ports the camera is perforated 

 by a cleft, into which fits a 

 metal piece capable of vertical 

 and horizontal movement. 

 Connected with this piece is 

 a rod, which, passing through 

 the table, ends in a wheel, the 

 teeth of which gear with those 

 of the head on the fine-adjust- 

 ment. The upper end of this 

 rod also carries a head, and by 

 turning this fine focusing is 

 effected. 



Schmidt and Haensch's 

 Apparatus for Photographing 



the Tarnish Colours of Iron Surfaces,* — The researches of Martens show 

 that correct pictures of the micro -structure of iron can be obtained by 

 allowing a perfectly level weakly etched iron surface to tarnish at a high 

 temperature, and observing it under the Microscope. Wedding found 

 that the details of the micro-structure are brought out in a much higher 

 degree if the iron surface is inclined obliquely to the axis of the Micro- 

 scope. The same should apply to the taking of a photomicrograph of 

 the surface. The camera which Schmidt and Haensch employ to this 

 end is a bellows camera, which can be drawn out to a length of 1 m. 

 The Microscope belonging to it has a low magnification, giving a field 

 of view of about 16 sq. mm. The stage can be fixed obliquely to the 

 optic axis of the Microscope by a mechanical contrivance. In this 

 oblique position it is clear that only one line across the field of view 

 will be sharply defined, and in order, then, to keep the stage and object 



1839. 



Zeitschr. f. Wiss. Mikr., v. (1888) pp. 225-6. 



2 I 



