SLEf.Vt- 



B08 



.BP- -..It 



Boring by Photography 



Keeping a Deep Hole Straight 



IN ALL deep borings the diamond drill 

 (lc\iatos considerably from its- starting 

 direction, and it is sometimes very desir- 

 able to obtain a survey of the hole. The 

 device here shown, which is the in\'ention of 

 Charles B. Galvin, of Cornwall-on-Hudson, 

 Xcw York, consists of a steel tube, ranging 

 trom fifteen to thirty feet long, with means 

 for indicating and recording any departure 

 of its axis from a straight line. A geometrical 

 straight line, tangent to the cur\ing axis of 

 the hole, is established by the projection 

 upon a disk of sensitized photographic 

 paper of the image of cross-hairs etcheci 

 on clear glass. Thus, if the hole is 

 perfectly straight the image of the 

 center of the cross-hairs will coincide 

 with the center of the paper disk, and 

 if not, the distance from the image of 

 the center of the cross-hairs to the center 

 of the disk rei)rescnts the amount of de\-ia- 

 tion or rate of curvature of the hole. 



The vertical and horizontal directions 

 are established on the paper prints by 

 means of the image of a weight, which 

 ma\- be cither a plumb-bob or a ball, free 

 to roll to the lowest point 

 immediately in front of the 

 paper. Adi.uneterdrawn through 

 the center of the paper anil the 

 center of the print of the ball or 

 axis of the bob indicates the 

 \ertical and the one at right 

 angles to this, the horizontal. 

 To these lines tlie lateral and 

 vertical deviations respectivch' 

 are referred. 

 A source of light, which ma>' be a one 

 or two-candlepower battery lamp, cur- 

 rent for which is supplied from the 

 surface via the cable, is situatitl in the 

 focus of a condenser-lens. A well-defined 

 image of the cross-hairs is thus projected 

 on to the paper tlisk at the other end of 

 the lube, b\' means of the objeiti\e lens 

 which is inter|)osed at the proper focal 

 distance between the cross-hairs and the 

 paper. The distance from the cross-hairs 

 to the objective would usualhbefrom two 

 and a half to three and a half or four feet 

 and from the objcctix'i- to the pa[)er, from 

 twi'Ke to twent\'-live or thirl\' feet. 



Applying the 

 photographing 

 device to a deep 

 bore to deter- 

 mine whether it 

 is straight or not. 

 The sensitized 

 photographic 

 paper is at the 

 extreme bottom 

 of the device 



Above: A pho- 

 tograph which 

 represents the 

 amount of devi- 

 ation or rate of 

 curvature of the 

 hole. At left: 

 The location 

 and arrange- 

 ment of the pho- 

 tographing de- 

 vice. The lamp 

 is at one end of 

 the tube and the 

 photographic pa- 

 per at the other 



7-20 



