AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 31 



through a system of lenses 14. It is found advantageous 

 for registering results to have a series of concentric circles 

 on the frosted glass plate 10, each circle corresponding to a 

 definite variation in the diameter of the borehole. A 

 kinematographic registration also suits the apparatus well, 

 in which case the hood 10 is completely replaced by a kine- 

 matographic recording device. When employing the latter 

 the motion of the apparatus down the hole must be uniform, 

 so the survey film obtained will yield an exact image of the 

 condition of the borehole or casing diameter. 



We will not deal with any of the old time-wasting and 

 tedious methods of single observations and records. 



PRESSURE RECORDS 



It is well known that in horizontal and inclined boreholes 

 the tendency to deviation is greater than in vertical ones^ 

 Although this tendency is mostly downward with horizontal 

 and upward with inclined holes, many holes, particu- 

 larly in inclined measures, tend to deflect upward. ^ Alter- 

 nating hardness, etc., also affects this. These deviations 

 are accentuated by the action of gravity and lower side 

 abrasion on the rods due to the weight of the crown. In 

 the case of horizontal and well-inclined boreholes (from 

 the vertical) maximum manometers are employed to 

 register the water pressure in the hole. 



The "Burbach" Pressure Recorder. — Where the deflec- 

 tion is downward, as in the usual cases, this method employs 

 the principle of gaging the pressure of the rinsing water 

 at various points in the borehole and contrasting these 

 records with the conditions at the borehole mouth. Where 

 the deflection is upward the pressure on the rinsing pump 

 may be gaged. 



a. When the borehole deviates downward, a tube piece is 

 screwed on to the boring rods. The apparatus of the 



1 Justice, J. N., Trans. Inst. Min. and Met., Vol. 12, p. 319; Kitchen, J., 

 ibid., Seventeenth Session, 1907-1908. 



2 Janson, Proc, Vol. 11, p, 48; Lake Superior Min. Inst., Vol. 2, pp. 26-30, 

 1894. 



