Archive image from page 72 of Deep borehole surveys and problems. Deep borehole surveys and problems deepboreholesurv00hadd Year: 1931 Plate III.—Koebrich's core orientation apparatus. V. Inside the cap are a clock and compass and the compass is arrested by the wing F of the clock U (Figs. 3, 4) moving clockwise, taking with it the lever arm h of the double- armed lever 1, 2, 3, (Fig. 5). In this way end 3 of the lever which is bent round engages the arresting spring / and frees it. This latter springs up and clamps the needle against the cover plate of the compass. A circular

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Archive image from page 72 of Deep borehole surveys and problems. Deep borehole surveys and problems deepboreholesurv00hadd Year: 1931 Plate III.—Koebrich's core orientation apparatus. V. Inside the cap are a clock and compass and the compass is arrested by the wing F of the clock U (Figs. 3, 4) moving clockwise, taking with it the lever arm h of the double- armed lever 1, 2, 3, (Fig. 5). In this way end 3 of the lever which is bent round engages the arresting spring / and frees it. This latter springs up and clamps the needle against the cover plate of the compass. A circular graduation about the axis of F is arranged so that the interval between

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