PHOTOGRAPHIC METHODS 



199 



as seen in Fig. 134d, where distances h, c and d are for 

 records 2, 3 and 4, respectively. Similar reasoning applies 

 to Fig. 135 showing clinometer records. Figure 136 shows a 



494.5/ ^j. jniended Course ofHole_ 



494.5'^'Jy]'j.~iJ)r,r-Course265'?60' 200' of Hole 30^ 

 Z20°Acfual4m ^""' 79^794° ?92 293 



289.5 



29i°294'' 292" 293 



P I d n 



Fig. 136. — Actual survey of a Portuguese borehole. 



typical borehole survey from Portugal constructed from 

 such records. We are indebted to the proprietors of 

 Engineering, and C. F. Casella & Co., London, the makers, 



Fig. 137. 



for the photographic views showing (Fig. 137) the compass 

 and chnometer, (Fig. 138) the casing and inner parts ready 

 for assembly and (Fig. 139) the clinometer and contact 

 drum. 



