PHOTOMICROGRAPHIC APPARATUS 15 



as it permits of the fine -adjustment head being reached 

 even when long extensions are employed. 



Van Heurck Camera. Dr. Van Heurck was the 

 greatest advocate of the vertical system and employed 

 it very largely, and a camera named after him made by 

 Messrs. Watson is a most rigid and efficient instrument. 

 It consists of a box standing on four legs over the micro- 

 scope, and connected thereto by a velvet sleeve ; it is 

 inextensible, and hence no change in the magnification 

 can be made otherwise than by a change of lenses. 

 There is a door in the front of the camera large enough 

 to allow of the head being inserted to examine the object 

 through the microscope, if desired, or to focus on a white 

 card in place of the ground glass (Fig. 71). 



Adjustable Vertical Cameras. Fig. 5 shows a modifi- 

 cation that can be made to fit any suitable camera 

 that may be at hand. It consists of a four-legged 

 support strongly and rigidly made. The top pieces 

 are rebated, so that the camera fits exactly and 

 firmly into them, but is removable at will. The base- 

 board of the camera also falls firmly into place on the 

 stand, and supports the front rigidly and permits of 

 any desired extension being made with ease. In this 

 it offers an advantage over the Van Heurck model, and, 

 to make use of different extensions easily, two bars are 

 screwed across the legs about 6" from the ground, and 

 across these a removable board is clamped to carry the 

 microscope, and, if desired, the illuminating apparatus. 

 Another pair of bars can be fitted higher up, or blocks 

 may be provided on which to raise the microscope still 

 more when a shorter extension is used. This stand has 

 proved very useful even for large pictures with an en- 

 larging camera, but generally when long extensions are 

 required the horizontal arrangement is better. In any 

 case, when making use of a particular camera its adapta- 

 bility to either method should be carefully studied, and 



