Oct. 5, i£88.] 



SCIENTIFIC NEWS. 



361 



SOME PHOTO-MICROGRAPHIC 

 APPARATUS. 



ONCE the initial difficulties are overcome, few occu- 

 pations are more instructive or engrossing than 

 photographing objects through the microscope. An 

 impression exists among people who have not tried it, 

 that photo-micrography is a very difficult branch of the 

 photographic art. This is undoubtedly true when very 

 high powers must be used, but it is not proposed to 

 treat of such matters here, but only to describe a simple 

 apparatus which can be acquired by most people, and 

 which can be successfully used by any person possess- 

 ing intelligence, a little manipulative skill, and patience. 

 The advantages of photo-micrography are that there 

 is little or no trouble in getting ready the apparatus ; 

 that photographs can be taken either in the daytime or 

 in the evening ; that the illuminating power being, if 

 artificial light be used, practically constant in intensity, 

 the variation of the exposure is dependent only on the 

 degree of magnification to be attained and the colour 

 and nature of the object it is desired to photograph, 



In arranging the apparatus it is advisable to procure 

 a piece of dry, well-seasoned pine or mahogany, 3 ft. 

 6 in. by 10 in. by i| in. thick, which will form a capital 

 base-board. 



Place the microscope on it, and bring the body of the 

 microscope into a perfectly horizontal position; then 

 with the greatest accuracy measure the distance from the 

 board to the centre of the tube of the microscope. This 

 will give the height of the optical axis above the base, 

 and it is of great importance to maintain this line per- 

 fectly parallel to the base, from the lamp to the focussing 

 screen of the camera. The centre line of the apparatus 

 should also coincide in plan with the centre line of the 

 base-board. 



Having determined the position of the microscope, 

 which should be about nine inches clear from the end 

 of the base-board, mark the position of the claw foot of 

 the microscope, and screw on small wood chocks or 

 clamps to hold it in position ; the microscope can then 

 be moved from the board and replaced in position as 

 desired. It is well also to fix a supporting block on the 

 base-board, upon which the tube of the microscope 



Fig. i. — Simple Photo-Micrographic Apparatus. 



thus eliminating the condition most difficult to deter- 

 mine in making a sunlight exposure, the ever-varying 

 actinic power of daylight. 



The absolute necessaries for taking a photograph 

 are, a lamp, a microscope, and a camera with a dark-slide. 



The lamp best suited to the purpose is the ordinary 

 microscope lamp, sold by any optician. This lamp has 

 a suitable screen or hood, with an aperture for the emis- 

 sion of the light, and facilities for turning either the flat or 

 the edge of the flame towards the microscope. A vertical 

 adjustment and a condensing lens are also desirable. 



The microscope may be of the simplest form, pro- 

 vided a good coarse and fine adjustment be supplied, 

 that it has suitable spring clips to the stage, and that 

 it is so constructed as to allow of the body being brought 

 into a horizontal position. A set of revolving diaphragms 

 beneath the stage is also of great value. 



A camera suitable for ordinary landscape photography 

 will meet the requirements of a beginner, though the 

 greater the extension of the camera the better. The only 

 necessary points to observe are, that absolutely no light 

 enters into the camera except that admitted through the ob- 

 jective of the microscope, and that the focussing screen and 

 the dark-slide occupy, when in position, the same plane. 



should bed when horizontal, thus ensuring the micro- 

 scope tube being readily brought to the required position. 



A suitable bed for the camera must next be prepared. 

 It will probably be found that the height from the under- 

 side of the base of the camera to its axis will differ 

 from that of the microscope, and that the camera will 

 require to be packed up to the requisite height ; this is 

 best done in the method shown in fig. 1. A slot, 10 

 or 12 inches long should be cut in the centre of the 

 supporting board of the camera, through which the 

 tripod clamp screw, usually supplied with a camera 

 will work. This arrangement will allow the camera to 

 be moved up to or away from the eye-piece end of the 

 microscope, and secured in any desired position. 



The junction between the camera and microscope is 

 best effected by means of a conical velvet funnel, secured 

 to the body of the microscope by an elastic ring, the 

 other end being passed all round the front of the camera. 

 This allows the adjustment of the microscope to be 

 readily effected, the eye-piece end of the tube working 

 through the lens aperture in the front of the camera. 



The lamp must then be centred, and should be 

 secured to the base-board by means of two rebated fillets, 

 between which it should work easily, thus enabling it 



