Archive image from page 100 of Deep borehole surveys and problems. Deep borehole surveys and problems deepboreholesurv00hadd Year: 1931 CORE ORIENTATION 89 an inertia motor is adopted. This is a heavy solid lead rotor 36 on a vertical shaft 37 suitably borne in bearings 38 and 39. It is so made that it will lag behind the rotation Plate VI.—Hanna's inertia-rotor apparatus. speed of the drill, thus continuing to rotate some time after the latter, owing to its momentum. On shaft 37 a worm gear 40 is engaged by a toothed projection 41 on a verti- cally movable rod 42 supported in frame

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Archive image from page 100 of Deep borehole surveys and problems. Deep borehole surveys and problems deepboreholesurv00hadd Year: 1931 CORE ORIENTATION 89 an inertia motor is adopted. This is a heavy solid lead rotor 36 on a vertical shaft 37 suitably borne in bearings 38 and 39. It is so made that it will lag behind the rotation Plate VI.—Hanna's inertia-rotor apparatus. speed of the drill, thus continuing to rotate some time after the latter, owing to its momentum. On shaft 37 a worm gear 40 is engaged by a toothed projection 41 on a verti- cally movable rod 42 supported in frame 19. As worm gear 40 rotates, with respect to rod 42 and its lug 41, rod 42

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