THE PHOTO-MICKOGRAPHIC CAMERA 119 



A vertical apparatus that presents some novel features is 

 that designed by Mr. J. W. Gordon, and made by Messrs. Beck 

 of Cornhill. It is so arranged that the object having once been 

 focussed in the microscope in the ordinary way, the camera 

 only has to be placed over it and the photograph taken no re- 

 adjustment of the microscope in fact being necessary to ensure 

 a sharp image on the photographic plate. It consists of a tube, 

 about six inches long, which is placed over the microscope eye- 

 piece when a photograph is required. At the upper end of this 

 tube a small photographic plate If inches square is held by 

 means of a cap ; between this and the eyepiece is a projection- 

 lens which focusses the image upon the plate, and a small 

 shutter for making the exposure is placed in the tube. If 

 the observer's sight is normal, the photograph will be sharp 

 when the microscope is in its proper visual focus ; but, as almost 

 everyone has some slight errors of vision, it is found desirable to 

 supply a duplicate tube with a focussing eye-piece of high power 

 which is first placed in position on the instrument and focussed, 

 and is then replaced by the camera. This apparatus therefore 

 becomes an essential part of the microscope, and since it is very 

 small and supported at such a short distance from the optical 

 system, it is less subject to the effect of vibration than some 

 other arrangements ; but still, in any case, it should be placed 

 so that it is as free from the influence of tremor as possible. 



Where a vertical camera is required simply as an adjunct to 

 a more complete and elaborate horizontal one, an improvised 

 arrangement such as Fig. 41 is as good as many at present on the 

 market. Anyone with a slight knowledge of carpentry can make 

 such an arrangement, or it can be constructed at a very small 

 cost by a mechanic. It consists simply of a baseboard about 

 twelve to fourteen inches square, and one inch thick ; underneath 

 this should be screwed two cross bracing pieces of the same 

 thickness in a direction across the grain of the wood, so that the 

 chance of warping is reduced to a. minimum. Two other lengths 

 of wood of the same thickness, each about three inches broad, 

 should be fastened together in T-form, as shown in the illustra- 

 tion, and these should be supported at right angles to the base- 

 board and firmly screwed down to it. On the flat side of this 

 vertical piece, another thinner piece of wood should be placed in 

 which is a narrow slot about three-eighths of an inch broad ; any 



