GB251429A - Method and device for detecting and locating ores by electromagnetic means - Google Patents

Abstract

251,429. Marks, E. C. R., (Aktiebolaget Elektrisk Malmletning). April 28, 1925. Locating conductors; magnetic tests. -Cores &c. are located by the disturbance they cause to an alternating magnetic field made to penetrate the ground, the ratio between the strength of the field at two points being determined by employing two test coils wound on frames I, II, and connected in opposition. In parallel with these frames is connected a telephone receiver or galvanometer T through an amplifier F. The frame I is placed at one of the points to be examined and its plane is varied until no sound is heard in the telephone T, indicating that the plane of the coil coincides with the direction of the field. The frame is then turned through a right-angle, so that its plane is at right-angles to the field. The frame II is then placed at the second point to be examined, connected in opposition to the frame I, and turned until no sound is given in the telephone T. The strength of the field is calculated from the angle between the plane of the frame II and the direction of the field. Instead of rotating the coil II, a variable inductance L may be connected in parallel or in series with the frame, and adjusted until no indication is given in the telephone. The ratio between the strengths of field at the positions of the two frames may then be calculated.