SEISMIC METHODS 



821 



holes in a raised base board to allow their easy removal for cleaning and 

 filling. Absorbent paper toweling will be found a convenience. 



A procedure is often used which avoids the need of a dark room, par- 

 ticularly in milder climates where the normal outdoor temperature is suit- 

 able for developing of records. The chemical containers are placed in a 

 light-tight tank. The cover of the tank consists of a frame to which a 

 hood is tightly attached, light weight leather being generally used for the 

 hood because of its ruggedness. The hood is equipped with a sleeve 

 through which the operator inserts one of his arms. The operator's free 





r^ 



Fig. 505. — Complete photographic developing equipment, a, record 

 storage compartment; b, drying racks; c, hot air circulating fan; d, oil- 

 burning stove; e, processing compartment; /, developer; g, stop bath; h, 

 fixing bath; ;, opaque cloth cover for front of compartment; ;', fresh water 

 washing tank; k, safety light for developing. (Courtesy of Continental 

 Oil Co.) 



hand is used to clasp the sleeve tightly to avoid light leaks. The magazine 

 is unloaded, the record developed, washed, and placed in the fixing bath 

 before the cover is raised from the tank. 



An advantage of this type of equipment is that the recording truck 

 need not be maintained light-proof, giving the operator greater freedom 

 of action and permitting him to attend to other matters while his sub- 

 ordinate proceeds with the developing. 



Figure 505 shows a complete photographic developing assembly with 

 heater, wash water can, and record rack. The heater is a modified 

 kerosene-burning stove, with a small fan for forced hot air circulation 



