PHOTOGRAPHING BUTTERFLY EGGS. 9 



out my arm along the side of the camera while I kept my eyes fixed 

 on the focussing screen. 



This somewhat primitive apparatus answered well so far as it 

 went, but I soon determined to work without the microscopic eyepiece, 

 and set to work, therefore, to build a very long extension camera. I 

 made it ^--plate size, so that the accessories I already possessed could 

 be used, and gave it a bellows 42in. long in three sections to obviate 

 sagging. I found this was a great improvement, but had, of course, 

 to get a much larger base-board, and used for this an oak plank 

 5ft. x 8in. x lin. The focussing of the microscope could not now be 

 done by hand, as the distance from the ground glass was too great for 

 my arm, so I carried a long brass rod through wooden blocks under 

 the camera, and fitted a small grooved pulley- wheel on it just under 

 the fine adjustment screw of the microscope, and put a milled 

 screw on the other end under the focussing screen of the camera. 

 A fine elastic band passed round the pulley-wheel, and the fine 

 adjustment screw then enabled me to focus comfortably, with my 

 head under the black cloth, by turning the milled screw already 

 mentioned. As the microscopic objective had to be brought very 

 considerably closer to the object in order to throw a sharp image 

 on the focussing screen than when focussed with the eyepiece in 

 the microscope alone, I noted from experiment the amount of this 

 variation by measurement, and screwed down the coarse adjust- 

 ment of the microscope the necessary amount before connecting it 

 with the camera, and, in this way, left only the final focussing to be 

 done with the apparatus described above. 



This answered much better and gave me many very excellent 

 results, but I was still not satisfied, as I found that, unless the ova I 

 wanted to take were small or had a comparatively flat upper surface, 

 only a portion of the resulting picture came out sharp, and all the rest 

 was out of focus, owing to the lack of penetration in the microscopic 

 objective. To improve this, I adapted a rapid rectilinear photographic 

 lens of 5in. focus to fit the body tube of the microscope in the place of 

 the usual objective, and, as this rendered the stage useless for holding 

 the object to be photographed, and the distance obtainable between it 

 and the lens was much too short for a lens of so long focus, I took 

 advantage of the circular opening in the stage to work through, and 

 fixed up a movable slide carrier in proper alignment working 

 behind the supporting block on which the microscope stood. This 

 was a great advance, but I was not, of course, able to get so large a 

 magnification as with the microscope objective, as, even with the aid 

 of a special extension which I fixed up between the camera lens front 

 and the microscope body tube, which enabled me to obtain a maximum 

 extension of 5ft. between the focussing screen and the lens, I could 

 only get a magnification of about ten diameters, while the exposure 

 required was nearly double. On the other hand, I had the advantage 

 of an iris diaphragm in the lens, so that I could focus with this open 

 to the fullest extent and admitting the maximum amount of light, and 

 then stop down to f. 16 or f. 22 for the exposure, and in this way get 

 the whole of the largest butterfly ova including even the background. 



A very powerful illuminant is an absolute necessity for this kind 

 of work. I started with a paraffin lamp, but soon found this useless, 

 not only on account of the amount of heat it gave out, but also owing 



