Patent GB-245698-A (GB)
Title: Improvements in instruments for use in surveying boreholes and the like
IPC: E21B47/022
Filed: 1925-10-03
Abstract: 245,698. Owens, J. S. Oct. 3, 1925. Borehole clinometers.-Relates to instruments comprising a plummet and a magnetic compass mounted in a gravity-controlled carrier arranged in a protective casing inserted into the bore-hole, means being provided whereby the indications of the elements are recorded on sensitized paper. According to the invention the external casing contains two carrier tubes in which are arranged the recording elements together with controlling mechanism for obtaining at one insertion a series of records of the deviations of the hole. The mechanism is contained in two tubes 12, 13, Fig. 9, connected by a bayonet &c. joint 14 and enclosed in the casing 1, the ends of which are closed by screw plugs 2, 3 containing spring plungers 6, 7 bearing on the ends of the tubes 12, 13. The recording elements are contained within the tube 13, the ends of which are closed by removables caps 18, 19, Figs. 1 and 2. The cap 18 is internally threaded to receive the threaded stem of a pivot-pin 15 and the cap 19 receives a pivot bolt 16 which is insulated therefrom. Mounted on and insulated from the bolt 16 is a sleeve 22 connected electrically to the cap 19, a second connection being made between the head of the bolt and one end of a dry battery 21 in the tube 12. Mounted on the pivots 15, 16 is a cradle 17 having near one end a bearing block 24 and near the other end a pillar 25, within which is mounted, so as to be insulated therefrom, a bolt 26 forming a bearing for the pivot 16. The cradle supports the clinometer, the compass, and two similar lamps arranged to illuminate one side of the clinometer and both sides of the compass. The lamp terminals 30, 31 are connected, one to the bolt 26 and the other to a finger bearing on the sleeve 22. Each lamp is enclosed in a casing 36 having apertures on opposite sides to project light along the tube 13; these apertures may be covered by screens of tinted glass &c. held in position by clips 37. The clinometer, Figs. 1 and 7, comprises a weighted drum 39 carried on a spindle 40 screwed therein, the ends of the spindle forming pivots seating in bearings 41 screwed into the cradle 17. The bearings are recessed and the recessed parts may be filled with a viscous oil to damp the oscillations of the drum. A sensitized strip 108 is wrapped round the drum and is retained by spring clips 43 arranged in such a position that they can never face the light. On the side of the clinometer facing the light is an apertured plate 44 exposing a strip 45 in which two apertures are formed; the remainder of the clinometer is protected from light by a coyer 46 and end plate 47. The compass, Figs. 2 and 8, is pendulously supported on pivots 54 in the cradle 17 and comprises a spherical-shaped bowl 49 with apertures giving access to a drum 51 carrying the record strips 107. The drum is mounted on the bowl by means of a shouldered bolt 56 and nut 57, a spring washer 58 being interposed so that the drum does not turn relatively to the bowl except when manually moved. The magnetic elements are mounted on a spider 62 supported by the pivot 71, and comprise a flat pair of needles 59 and a pair 60 on edge. The spider 62 is formed with two diametrically-opposite triangular apertures 63, 64 adjacent the strips 107 and also carries two dead white matt surface reflectors 65, each inclined at 45<c>. A translucent dome 48 is supported by a ring 75 which also carries a bridge 73 with an aperture 69 forming a steady bearing for an extension 68 of the spider 62; the ring also carries a diffusing screen 77. The compass is covered by a hood 78 with a dead white inner surface to ensure uniform illumination of the dome. The controlling means, Figs. 5 and 6, within the tube 12 consist of a dry battery 21 and a clock 87 operating means for closing the circuits of the lamps at determined intervals, the total number of exposures and the duration of each being also controlled by this device. A disc 80 secured to the tube 12 has an extension 81 graduated by lines representing hours, and also carries axially an insulated left-hand screw 82 secured thereto by nuts 83, 84; within the nut 83 is a spring plunger 85 making contact with the battery 21. The screw 82 engages in a long axial nut on a member 91 to which is secured a drum 86 of insulating material having graduations representing quarter-hours on its rim 94. The drum carries four contact strips 95, 96 electrically connected to the flange 93 of the member 91, these strips being of such widths that a series of exposures of increasing length are obtained at each complete revolution of the drum. A pair of contact fingers 98. 99 secured and electrically connected to the tube 12 bear on the drum to complete the lamp circuit each time one of the strips passes beneath them. The drum is rotated by a crank 88 on the minute-hand of the clock operating a pin 90 projecting from the member 91.