PHOTOGRAPHIC METHODS 179 



dried by forcing through sulphuric acid. After lowering 

 the camera tube into the water it was raised to the surface 

 to see if in cooling any moisture had been precipitated 

 on the inside of the window. The window was found to be 

 dry and clear, and upon lowering the second time, the expo- 

 sures were made without any regard to the location of ore 

 bodies. The device is now chiefly of historic interest and its 

 limitations are obvious, however its principle still survives 

 vigorously. 



Reinhold's Photographic Apparatus. — This device was 

 invented in 1924^ by Thomas Reinhold, Chief Geologist 

 of the Geological Survey Department of Holland, and 

 described at the International Congress of Geology at 

 Madrid in 1926. 



Its purpose is to provide a photographic record of the 

 strata pierced so as to obtain the nature of the same, 

 detect the presence of fissures and to get the dip of the beds. 

 It will be seen to be additional to ordinary core orientation 

 or borehole deviation methods, since it photographs the 

 walls of the unlined part of the borehole. 



The apparatus shown in Figs. 118 and 119 is attached 

 to the upper end of the drill rods and then lowered to the 

 required spot in the hole. It will be noted that a section 

 of the hole is isolated in a watertight manner at the upper 

 and lower ends by means of the packing rings x and y. 

 This length of the borehole is then washed out by means 

 of clean water, the wall is illuminated, and a photograph 

 is taken. The photographic apparatus is enclosed in a 

 strong bronze tube between the packing rings, the film 

 camera being placed in the chamber h. Two electric lamps 

 / illuminate a part of the wall g. The rays of light pass 

 through the glass and are reflected upward from the reflector 

 d to the lens c, throwing an image on the film k in the 

 camera. A small electric motor a changes the exposed part 

 of the film for a fresh one after each exposure. Enough 

 film is provided for obtaining a few hundred exposures, one 



^ British Patent No. 226,079; see also Colliery Engineering, p. 371, August, 

 1926. 



