GB191514780A - Improvements in Instruments for Surveying Drill Holes. - Google Patents

Abstract

14,780. Galvin, C. B. Oct. 19. Tell-tale apparatus.- Apparatus for surveying drill holes comprises a carrier containing a movable member of magnetic or non-magnetic material, such as a rolling ball or pendulum, and a lamp, the circuit for which is automatically completed when the carrier is in the desired position, to produce an image of the movable member on a photographically sensitive film. In one form, the upper part of the carrier 11, Fig. 4, contains a ball 22 rolling on a transparent disk 20 beneath a film 18, and also an objective 29. The lower part of the carrier 13, Fig. 5, contains a battery comprising cells 40, 41, 42, a lamp 24, a condenser 25, and a reticule 26 having radial or intersecting cross-hairs or concentric circular hairs. The lamp circuit is completed when a spring 47, carried by a plunger 49 secured to a drill rod 16 of desired length, is forced into contact with the zinc casing 45, forming an electrode of the lowest cell, by the contact of the bottom of the drill rod 16 with the bottom of the hole. The position of the image of the ball relative to the image of the hairs determines the deviations of the drill hole. A modification in which the closing of the lamp circuit is postponed comprises a movable cylinder which surrounds the spring 47 and the head of the plunger 49. The movable cylinder is contained in an outer cylinder holding fluid, and has a perforated top through which the fluid slowly passes and permits its slow movement in an outer cylinder to complete the circuit. The relative position of the parts may be reversed.