PHOTOGRAPHIC METHODS 



189 



lenses can also be set here. On the upper surface of the 

 level is a mark a a (Fig. 129) representing the abscissa 



The 



Fig. 129. 



axis on which the direction of the throw is taken 

 two convex lenses g and h from 

 which the latter is screened throw 

 the image of the level with the con- 

 centric rings, the abscissa axis, and 

 the upper needle ns (Fig. 129) on to 

 a sensitive paper strip i (Fig. 128) 

 working on rolls Ri and jB2 and 

 shafts r, r. This is the headpiece 

 with registering device shown in Fig. 

 128. Below the frame (not visible 

 in Fig. 128) is a central lug for stick- 

 ing in the casing. There are connec- 

 tion screws for the level and the 

 whole frame, for connection and 

 screwing in the frame to the cylin- 

 drical casing. 



The Registering Apparatus. — This 

 is shown in Fig. 130 on a greater 

 scale than in Fig. 128. A long strip 

 of paper very sensitive to light winds 

 from a roll Ri over two guide roll 

 shafts r in the image plane of the 

 level and lens system. From here it 

 runs on over the fixed drive roll R2. 

 There is a solenoid e above the rolls provided with a clutch n 



Fig. 130. — Haussmann's 

 registering apparatus. 



