SEISMIC METHODS 829 



With the photo-sensitive material passing these recording images at a 

 constant velocity, the variations in geophone outputs within the desired 

 band will be represented as density-modulated sound tracks quite similar 

 in their general appearance to the earlier Sonograph records. 



The drive mechanism for moving the recording material is provided 

 with a commutator to trigger the shooting current. Suitable safety inter- 

 locks prevent the accidental discharge of the firing cap as well as accidental 

 exposure of the recording material. The exposed film is handled throughout 

 the entire development process by automatic controls to obtain a uniform 

 average density for successive recordings. 



The purpose of the analyzing equipment is to translate the total infor- 

 mation contained in the memory record into a visual form more suited to 

 interpretation. 



It is proposed that by means of a photoelectric system for changing 

 the individual variations of density of the recorded sound tracks into 

 pulsating electrical energy, the original information will be altered to 

 trace, on the fluorescent face of a cathode-ray tube, an image showing a 

 cross-section of the earth under investigation. By entering known data 

 pertaining to conditions surrounding the original field recording, with the 

 additional faculty on the part of the examiner to vary such assumptions 

 as the interpreter normally introduces in his analytical procedure, this 

 image may be changed at will to indicate the effect of his introductions. 



It is proposed to introduce as electrical parameters the knowledge 

 gathered through well surveys, core samples, surface geology and the like, 

 to obtain a more coherent picture of the geological formations under 

 investigation. The computing equipment which produces the locating signals 

 for the electron beam of the display tube is to perform, through successive, 

 rapid calculations, the mathematical operations necessary to solve the inter- 

 preter's problem. Under this proposed plan the examiner will be able to 

 vary the plane of the cross-section viewed on the screen so that it will con- 

 tain information concerning dip, hade and depth relationships of the 

 various strata. 



When a series of known and assumed data has been introduced into the 

 computing machine and a picture which seems logically related to these 

 data has been obtained on the screen, a photograph of the image, as well 

 as of the assumptions, will be made for future reference and comparisons 

 to similar photographs made of adjacent investigated areas. 



Frequency Analysis. — A third system utilizes a wave analysis tech- 

 nique whereby the complex seismic wave is broken down into its different 

 frequency components. Analysis and interpretation are then made by 

 correlation of these components. f 



t J. J. Jakosky, method and apparatus patents pending. 



