124 PEACTICAL PHOTO-MICROGRAPHY 



of any transparent objects. The whole apparatus is supported 

 on a stiff base, the camera having a considerable extension 

 and being sufficient for high-power work. The optical system 

 and the illuminant are carried on a triangular metal bar, 

 so that any part of the apparatus may be adjusted in the 

 direction of the axis of the microscope, or can be removed and 

 replaced at will without alteration of position and without the 

 necessity of re-adjustment. The base of the camera is in two 

 parts, the one telescoping into the other, and it is so arranged 

 that when only a short camera is in use there is practically no 

 extension of the base to interfere with an observer, enabling 

 him the more easily to manipulate the apparatus from the rear. 

 The bar carrying the illuminating system is attached by 

 means of a clamping-screw, and takes a bearing on a plate 

 sliding along the top of the base. The other end is supported 

 on a foot with ball castors, which rests on the table or bench 

 supporting the whole apparatus and is provided with adjust- 

 ment to regulate the height. The bar can be arranged so that 

 its near end is in close proximity to the plane of the microscope 

 stage, or it may be set back so that it is as much as eight inches 

 distant. Near the position occupied by the stage of the 

 microscope a side carriage is arranged which has a limited 

 travel to and fro, and upon which are fittings to receive the 

 metal bar when illumination of an opaque object is desired. 

 The position of the bar carrying the optical apparatus 

 can be adjusted from the end of the baseboard which 

 supports the focussing-screen of the camera. Although this 

 arrangement seems an unnecessary elaboration, it may under 

 special circumstances prove of value. In any apparatus, 

 however, the microscope and illuminant should be arranged 

 in such a way that no further adjustment is necessary when 

 they are swung into position in relation to the camera and are 

 therefore ready for photographing. The fine-adjustment of 

 the microscope is manipulated from the focussing-screen of 

 the camera by means of a milled head substantially in the 

 same manner as already described with the simpler apparatus. 

 The chief characteristic of this apparatus is clearly the method 

 of swinging out the optical part of it so as to make it available 

 for work with opaque objects. 



A more complete apparatus and one embodying arrangements 



