MEDIUM-POWER PHOTO-MICROGRAPHY 53 



loth to enter on the subject of photo-micrography on account of the initial expense, we 

 feel tempted to describe a cheap form of arrangement which we can vouch for as being a 

 practical one, as all the photos in this book have been taken with it either by my son 

 or by myself* There is 7iothing original or even novel to especially recommend in 

 it, save that of utility and cheapness ; and that the camera used is only an ordinary 

 quarter-plate one (or half-plate if desired) ; and that it can be made by any one who 

 has tools at his command or can employ a carpenter of ordinary intelligence. (Figs. 

 24a and 24b.) 



If the reader will refer to the chapter on low-power photo-micrography (p. 24), 

 he will see there described how the camera was recommended to be fitted to a certain 

 form of wooden block, all dimensions being given. It will be further seen on looking 

 towards the end of the description that a second simple form of railed board was 

 advised to be made wherewith to take the photos of the culture tubes (pp. 26, 27). 

 Another of these should now be constructed, but of still more solid character — the 

 board itself being il inches thick, 4 feet 6 inches long, and 9 inches wide, and 

 attached permanently to the table — whether with legs or slung — by strong screws 

 passing through rubber washers. A central line should be firmly drawn along the 

 table corresponding with the axis of the camera when in situ. 



The focussing-rod arrangement is novel to a small degree — as seen in the blocks 

 Figs. 24a and b, and Fig. 24c. It is supported by a square piece of wood, better 

 seen when looking at the plan diagram. The pulley end is capable of movement 

 laterally, turning upon the pin, also shown. When arranging the silk cord passing 

 from the fine adjustment to the pulley on the focussing- rod, the piece of wood is 

 brought near to the microscope, thus enabling the operation to be done quite easily. 

 After it has been passed over both (the pulley and the fine -adjustment screw) the 

 wood is pushed away from the microscope and fixed there by a thumbscrew, just 

 visible in the plan diagram at the foot of the exposure shutter, passing through a 

 slot into the table. This method is convenient, as any stretching of the cord can be 

 taken up as much as necessary, and it enables the operator to slip on the cord 

 without disturbing the focus to any sensible amount. 



It is not difiicult to understand on looking at Figs. 24a, b, or c, that the camera 

 slides to and fro between the rails fixed in the base-board of the apparatus. It not 

 only slides to and fro, but takes completely off when the wooden screws are unloosed. 

 By this simple means the camera in its entirety can instantly be transferred to either 



* The whole of the photographs of the "Atlas of Bacteriology " were also taken on this stand. Some are reproduced 

 in Plate V. of this work through the kindness of the Publishers. 



