. Deep borehole surveys and problems. Boring. 98 DEEP BOREHOLE SURVEYS AND PROBLEMS 2. With some fluids capillarity effects are harmful to the readings, especially in small diameter boreholes. 3. Turning of the apparatus in the hole either on going down or on being raised out nullifies the direction results but not the amount results for inclinations. 4. The centering of these devices is usually neglected. Nolten's Method.—The oldest method applying the fluid principle is probably that introduced by G. Nolten, a district counselor of Dortmund in 1873.^ Hydrofluoric acid is used as the fluid wh
. Deep borehole surveys and problems. Boring. 98 DEEP BOREHOLE SURVEYS AND PROBLEMS 2. With some fluids capillarity effects are harmful to the readings, especially in small diameter boreholes. 3. Turning of the apparatus in the hole either on going down or on being raised out nullifies the direction results but not the amount results for inclinations. 4. The centering of these devices is usually neglected. Nolten's Method.—The oldest method applying the fluid principle is probably that introduced by G. Nolten, a district counselor of Dortmund in 1873.^ Hydrofluoric acid is used as the fluid which eats an outline at its surface on a glass cylinder. The direction of the deviation is obtained from a clockwork arrested magnetic needle in a cylinder fixed to the fluid vessel. In Fig. 48 is shown the vessel of colorless glass having an exactly cut base with per- pendicular walls. If the vessel is half filled with dilute acid and left about half an hour in an inclined position we get the etched mark ah (Fig. 49). If we now lay the vessel horizontal we get another mark cd. If we draw a parallel to dc through a, then in the triangle ahf resulting we know sides af and hf so that angle haf can be determined. In the hole the glass vessel is encased in a watertight, sealed measuring cyhn- der c. This is connected by a screw spindle I to the rods or rope (the whole internal part can be extracted from the shell on this spindle). Gutta- percha discs a and ai guard the apparatus against concus- sion shocks. The top opening of the measuring cylinder has three notches 60 deg. apart which are for fitting on three corresponding plates X, Y and Z. After putting in the plates they are locked fast by a 60-deg. turn. The locking screw goes through plate X. On the lowest plate Z stands the glass cylinder c which has a fixed graduation 1 See also Redmatne, R. A. S., Vol. 1, and Pr. Zeitschrift., Vol. 27, p. Fig. 48.—Nolten's Please note that these images are extracted fr
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