On the switchboard serving the compass there is a reversible motor, two of the windings of which are constantly connected to a generator—the same generator as serves the gyro-motors. The contact ball R is connected to the third phase of the generator, while the two strips P Q are connected to the third winding of the reversible motor, this winding being duplicated in such a way that the motor revolves in one direction or the other, according as the circuit is completed at the ball R through the strip P or the strip Q. A commutator is mounted on the axle of the reversible motor, and from it current is distributed to the motors operating the repeaters and to the “follow-up” motor S ([Fig. 51]). The latter motor is geared to the shaft carrying the bowl C, and when started up by the reversible motor turns the bowl in the direction required to restore the ball R to the middle of its slot, and so break the connection with the strip P or Q. Thus when the ship’s course is altered the bowl tends to rotate with the ship, but the ball R is mounted on the sensitive element, and therefore maintains its position. Contact is thus established between the ball and one of the strips P Q, the reversible motor is set rotating in the appropriate direction, and current is distributed to the “follow-up” motor S to rotate the bowl relatively to the ship until the ball R is once more lying midway in the gap. The tendency of the bowl to rotate with the ship is thus counteracted; the action of the “follow-up” motor practically results in the bowl being held in constant relationship to the sensitive element substantially as though it were part thereof. Simultaneously the cards of the repeaters are prevented from rotating with the ship, so that virtually they, too, act as if rigidly connected to the sensitive element, without, however, any frictional drag being thrown from them on to the sensitive element.
As illustrating the refined construction of the entire compass, the design of the ball contact may be noticed. The ball is carried at the end of a tapered spiral spring. It is free to rotate on the spring end, but is prevented from moving axially thereon. The spring end is provided with a button. The ball is drilled out and beaded over the button. To ensure good electrical contact at all times between the ball and the spring a drop of mercury is carried inside the ball between it and the button. Should the ship turn very suddenly the ball may spring out of the gap and be dragged across the face of one or other of the strips P Q. It is for this reason that these strips are silver-plated.
The repeater compasses are provided not only with an ordinary card graduated from 0 deg. to 160 deg., but also with an inner dial which makes one revolution for an alteration of 10 deg. in the ship’s course. This dial is graduated to 1/10 deg., and permits very small departures from the set course to be immediately noticed and corrected. An elaboration of the same idea is provided in the multiple repeater of the Brown compass. In this repeater the inner dial is the ordinary 360 deg. card. The outer annular dial makes four revolutions for every complete turn of the ship. With the ship sailing due north the graduations on the outer dial are numbered from 0 to 45 round the east half of the dial, and from 360 to 315 round the west half. The numbers, however, are not marked on the dial itself, but on the edges of discs seen through slots in the dial. As the ship turns from the north towards the east, the discs on the west side of the dial are successively rotated one stage as the south end of the lubber line passes over them, so as to exhibit numbers forming a continuation of the numbers on the east side of the dial. The outer magnified dial is thus of itself sufficient for navigational purposes.
In the Anschütz equipment arrangements are made for attaching an azimuth mirror to the repeater dial for the purpose of providing an artificial horizon during the taking of bearings. A separate gyroscopically stabilised artificial horizon device, such as is sometimes to be found on board ships, is thus rendered unnecessary.
INDEX
- Absence of latitude error in Anschütz (1912) compass, [158]
- Absence of latitude error in Brown compass, [66]
- Action of excentric pin in Sperry compass, [55] et seq.
- Air-blast pressure, Brown compass, [61]
- Anschütz (1910) compass—
- Air-blast damping system, [42] et seq.
- Damping curve, [50]
- Latitude error, cause of, [65]
- — — correction for, [67]
- — — value of, [68]
- Magnitude of directive force at equator, [23]
- Non-gyroscopic details, [138]
- Period of vibration of axle, [33], [37]
- Peripheral speed of wheel, [47]
- Quadrantal error, [96], [107], [120]
- Weight, diameter, and speed of wheel, [23]
- Weight of sensitive element, [30]
- Wheel tested to destruction, [140]
- Anschütz (1912) compass—
- Absence of latitude error, [158]
- Directive force, value of, [125]
- Fourth gyro type, [128]
- Gyro-wheels, details of, [159]
- Non-gyroscopic details, [154]
- Oil damping system, [156]
- Quadrantal error, [107], [120], [126]
- Repeater compasses, [162]
- Temperature rise, [160]
- Weight, diameter, and speed of wheels, [123]
- Ballistic deflection and error, [81] et seq.
- Ballistic deflection, dead-beat, [87]
- Ballistic deflection, tests by British Admiralty, [89]
- Ballistic gyro, Sperry compass, [111]
- Brown compass—
- Absence of latitude error, [66]
- Air-blast pressure, [61]
- Compensator weights, [134]
- Damping bottles, [61]
- — system, [59] et seq.
- Generation of directive force, [116]
- Magnitude of directive force at equator, [23]
- Non-gyroscopic details, [148]
- Oil control bottles, [113]
- On due west course, [117]
- Quadrantal error, [113], [126]
- Repeater compasses, [154], [162]
- Weight, diameter, and speed of wheel, [23]
- Weight of sensitive element, [30]
- Centrifugal forces during quadrantal rolling, [130] et seq.
- Clock, gyroscopic, [16]
- Compensator weights, [134]
- Correction mechanism for latitude and north steaming errors, [75]
- Course correction or cosine ring, [77]
- Damped and free motion of gyro-axle, [49]
- Damped and undamped vibrations, [35] et seq.
- Damping curve, [50]
- — systems, [42], [43], [52], [59], [156]
- — vibrations of gyro-compass, [29]
- Dead-beat ballistic deflection, [87]
- Details of gyro-wheels, [23], [159]
- Directive force, value of, at equator, [23], [125]
- Directive force, effective, [28]
- Effect of rolling on due west course, [93], [98], [99]
- Effect of rolling on due north course, [94]
- Effect of rolling on north-west course, [101]
- Elementary gyro-compass, [18]
- — — at equator, [20], [26]
- — — at [55] deg. N. lat., [24]
- — — near North Pole, [26]
- Elementary gyroscope at equator, [15]
- Elementary gyroscopic phenomena, [4] et seq.
- Elimination of the quadrantal error, [107]
- Excentric pin, action of, [55] et seq.
- — — stabilisation of, [110], [112]
- External gimbal mounting, [13], [97]
- Fourth gyro type of Anschütz compass, [128]
- Free and damped motion of gyro-axle, [49]
- Friction, solid and fluid, [39], [40]
- Generation of directive force, [18], [116]
- German submarines, [96], [120], [128]
- Gimbal mounting, external, [13], [97]
- Gyro-axle, free and damped motion of, [49]
- Gyroscope at equator, [15]
- — with three degrees of freedom, [4] et seq.
- Gyroscope and rotation of the earth, [15]
- Gyroscopic compass at equator, [20], [26]
- Gyroscopic compass at [55] deg. N. lat., [24]
- Gyroscopic compass near North Pole, [26]
- Gyroscopic phenomena, elementary, [4] et seq.
- Gyro-wheels, details of, [23], [159]
- Latitude bail corrector, [69]
- — corrector dial, [76]
- — error, [65]
- — — absence of, [66], [158]
- — — cause of, [65], [66]
- — — correction of, [67], [75]
- — — value of, [68], [69], [75]
- Magnetic compass, [1], [23], [30]
- Magnitude of directive force at equator, [23], [125]
- North steaming error, [70]
- — — — correction mechanism, [75]
- — — — value of, [74], [79]
- Oil control bottles, [113]
- — damping system, [156]
- Pendulum, simple, [31], [81]
- Period of rolling of a ship, [95]
- — — vibration of gyro-axle, [33], [37], [88]
- Peripheral speed of gyro-wheel, [47]
- Phantom ring, [53]
- Quadrantal error, [91], [96], [107], [120]
- Quadrantal error, elimination of, [107], [108], [113], [120], [126]
- Quadrantal error, value of, [107]
- — rolling, centrifugal forces during, [130] et seq.
- Repeater compasses, [79], [80], [146], [152], [162]
- Rolling of a ship, period of, [95]
- — on due north course, [93], [98], [99]
- — — — west course, [94]
- — — north-west course, [101]
- — quadrantal, centrifugal forces during, [130] et seq.
- Rotation of the earth and the gyroscope, [15]
- Simple pendulum, [31], [81]
- Sperry compass—
- Bail, [54]
- Ballistic gyro, [111]
- Compensator weights, [134]
- Course corrector or cosine ring, [77]
- Damping system, [52]
- Directive force, magnitude at equator, [23]
- Excentric pin, action of, [55] et seq.
- Excentric pin, stabilisation of, [110], [112]
- Latitude bail corrector, [69]
- — corrector dial, [76]
- — error, cause of, [66]
- — — correction of, [67], [75]
- Latitude error, value of, [69]
- Non-gyroscopic details, [142]
- North steaming error, correction of, [75], et seq.
- On north-west course, [108]
- Phantom ring, [53]
- Quadrantal error, [108], [126]
- Repeater compasses, [146]
- Speed correction dial, [77]
- Vacuum in wheel casing, [52]
- Weight, diameter, and speed of wheel, [23]
- Weight of sensitive element, [30]
- Submarines, German, [96], [120], [128]
- Temperature rise in Anschütz compass, [160]
- Test of Anschütz wheel to destruction, [140]
- Vacuum in Sperry casing, [52]
- Vibration period of Anschütz compass, [33], [37]
- Vibration period of gyro-axle, standard, [88]
- Vibrations, damped and undamped, [35] et seq.
- Weight, diameter, and speed of gyro-wheel, [23], [123]
- Weight of sensitive element, [30]
Printed in Great Britain at
The Mayflower Press, Plymouth. William Brendon & Son, Ltd.
FOOTNOTES
[1] Earlier form as in use in 1910.