ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1025 



the tube with a pencil, aud the fly will soon show its head through the hole 

 in the disc. The tube is then taken away, and the wool plugged up in the 

 cone to keep the fly in its place. A pair of stage forceps, with the ends 

 made hollow like a pair of gasfitter's pliers, can be used to hold the 

 cone. 



Mr. Macer showed a living house-fly with this apparatus, at the 

 November Conversazione, in a very effective manner. 



(4) Photomicrography. 



Nelson and Curties's Photomicrographic Camera. — At the November 

 meeting of the Society Mr. E. M. Nelson read the following description of his 

 photomicrographic camera (fig. 244) * : — " Mr, C. L. Curties and myself have 

 designed this camera in the hope of combining efficiency with simplicity. 

 The points in its construction are as follows : — A board on iudiarubber feet 

 of sufficient length to take lamp, Microscope, and camera when fully extended. 

 The usual chocks to hold the Microscope feet, and the fine-adjustment 

 focusing-rod on the right-hand side of the board. The camera made of two 

 square f tubes of cardboard sliding one inside the other. Upright wooden 

 ends to hold the cardboard tubes ; these slide in grooves in the base board, 

 and are fixed by clamping-screws. The front board has a brass nozzle to 

 fit into the light-excluding cap on the Microscope. The back board is 

 grooved to receive the focusing-glass and the double back. The light- 

 excluding cap is made of cardboard covered with leather, which is as efficient, 

 and not so heavy, as the ordinary brass ones. The double backs are of iron ; 

 they are about one-sixth of the cost, and far smoother in their action, than 

 mahogany ones. There is a fitting to hold diaphragms in the back. 



The method of working is as follows : — The Microscope, inclined to a 

 horizontal position, is placed in the chocks, the camera closed up, and slid 

 back as far as it will go to the other end of the board. There will now be 

 plenty of room between the camera and the Microscope for the eye to be 

 conveniently placed to the eye-piece. The lamp, condenser, &c., are now 

 centered in the usual manner, and a critical image of the object received by 

 an ordinary eye-piece. When all the necessary adjustments are completed, 

 the ordinary eye-piece is removed, and a projection eye-piece substituted for 

 it. The camera, still closed, is now slid up to the Microscope, leaving suffi- 

 cient distance between them to allow the hand to focus the eye-lens of the 

 eye-piece. Next let a piece of paper be held up in the position the back 

 will occupy when the photograph is being taken, and the diaphragm of the 

 eye-piece focused, by means of the eye-lens, sharply upon it. The camera 

 is now slid up to the Microscope, and the nozzle inserted in the light- 

 excluding cap. The camera is now extended to the required distance, and 

 the object focused on the plate in the usual manner. 



The following are a few hints in the use of the above camera : — It is not 

 advisable to push magnifying power more than ten times the initial power 

 of the objective. To this end the camera has been designed for use with 

 Prof. Abbe's lower-power projection eye-pieces, as he recommends the lower- 

 power eye- pieces in preference to the higher when sufficient camera length 

 can be obtained. 



A plain glass screen is recommended in place of the usual ground glass. 



The best focusing-lens is an aplanatic lens of six power by Zeiss 

 (Catalogue No. 127). 



* Described ante, p. 661. 



t As shown in the fig. these are round ; they were subsequently made square on the 

 suggestion of Mr. J. Mayall, junr., as being more serviceable in that form. 



