SEISMIC METHODS 



839 



Where climate requires, the truck, especially the roof, should be ther- 

 mally insulated for work in hot summer months. Means should be pro- 

 vided for fan ventilation in summer and heating in winter. The truck body 

 must be light- and dust-tight to provide the necessary dark-room facilities. 



Fig. 521. — A 12-trace portable seismic outfit 

 at a station clearing in the Philippines. (A) 

 amplifiers; (B) camera magazines; (C) viewing 

 window; (D) galvanometer and timing machine: 

 (E) carrying litter. (Courtesy of Geophysical 

 Engineering Corporation.) 



Fig. 522. — ■ Developing seismograms in day- 

 light using portable equipment, in Philippines. 

 (Courtesy of Geophysical Engineering Corpora- 

 tion.) 



B 



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Fig. 523. — Instrument truck body, with power-driven reel, mounted on 

 four-wheel drive truck. A, door to instrument compartment and dark-room; 

 B, reel; C, seismometer storage, battery compartment, etc. (Courtesy of 

 Century Geophysical Corporation.) 



Provision must be made for carrying extra equipment, such as augers, 

 spades, pick-axe, small tools, and emergency water and canned food rations. 

 The recording truck must be provided with the necessary photographic 

 paraphernalia for processing the records. 



