24 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



of the graph paper n is caused by the sinking of the rods a. 

 A hook e on a ring on the boring spindle catches in the chain. 

 This chain runs over the rollers g, gi and g2 and is kept 

 taut by the weight h. The motion of the roller g is trans- 

 mitted by means of a bevel wheel on the shaft I so that the 

 paper moves corresponding to the deepening of the borehole. 

 The speed of the paper depends on the transmission between 

 the bevel wheels i and k. The pen moves on an endless 

 chain p (Fig. 4) at right angles to the direction of the drum 

 graph, and it is driven by the toothed wheels q and q^. 



iJL^ M fiS, 



i 



1 



Fig. 4. 



Fig. 4a. 



Fig. 4. — Jahr's stratigraph — the recorder. 



Fig. 4a. — Showing relation of record to measures for estimating depth 

 thickness of beds. 



and 



The chain is driven by belting r from the driving shaft 

 of the engine *S. The recorder has several pens m^, m^, 

 etc., spaced on the chain p at vertical distances equal 

 to the depth of the record paper. Whenever a pen reaches 

 the top edge of the paper it leaves it just as the next lower 

 pen comes into action to continue the record, since their 

 distances apart equal the depth of the graph paper. Thus 

 the record is got as a continuous series of broken lines 

 which can be cut and arranged later if desired. 



It will be seen that the quicker the boring rods sink the 

 more the curve will approach the abscissa direction and 

 there will be a change in the curve for every different speed 



