An early electric motorised gyroscope Unsigned, bearing a collection accession number suggesting a date of circa 1886 With heavy turned brass flywheel mounted on an arbor with pin pivots at each end and incorporating twin triangular section rotors set between a pair of horseshoe-shaped electromagnets with green silk insulated windings positioned within the inner ring of the dual-axis gimbal assembly, the whole mounted via hinge joint and ball-race rotation bearing onto a baluster-turned lignum vitae upright over large moulded mahogany disc base inscribed in white ink 1886-29 to leading edge, 37cm (14.5ins) high. Although the unusual properties of a rotating flywheel had been observed since ancient times the importance of the gyroscope as a potential navigational aid was first established by Leon Foucault in 1852. In that year he constructed apparatus which incorporated a gimballed gyroscope assembly (of the form that became relatively standard from that time onwards) in order to demonstrate the earth’s rotation; Foucault also coined the name for the apparatus based on the Greek word for rotation gyros. At around this time a very similar mechanism was independently devised by the German schoolteacher Friedrich Fessel. It was this apparatus which Charles Wheatstone chose to discuss in his 1864 essay entitled On Fessel’s gyroscope which was published in the Proceedings of the Royal Society of London, vol. 7, pages 43-48. The use of an electric motor to provide indefinite motion to a gyroscope is thought to have first been applied during the 1860’s. This advance lead to the potential practical application of the gyroscope as a heading indicator, with further subsequent development resulting in the first practicable gyroscopic compass being patented in 1904 by the German inventor Hermann Anschütz Kaempfe. It is perhaps appropriate to suggest that the current lot may have been made as a demonstration model to illustrate how a simple gyroscope can be made to seek True North by the addition of a pendulous weight applied to the gimble which imparts a precessional force as the Earth rotates underneath it, with the outcome that the gyro ends up aligning itself to the Earth's axis. The two pulleys at the top and bottom of the outer gimbal are believed to be for this purpose. The mechanism is particularly noteworthy in that it employs an unusual design of motor to drive the flywheel constructed with two horseshoe-shaped electromagnets facing each other with the space between occupied by the spin axis arbor of triangular section with rounded apexes. The lack of brushes and unusual profile of the arbor would suggest that drive is enabled via alternating magnetic attraction as the triangular rotor's gap with the stator changes. The presence of two pairs of opposing coils would indicate that the assembly would require a pulsed power supply which, during the late 19th century, could have been supplied by an alternator. When the design and proportions of the rotors are considered it is probable that the efficiency of the motor would be very low, however for the purpose of maintaining the motion of the gyroscope the small amount of torque provided would have probably been sufficient. The white ink numeric inscription to the base of the current lot conforms to museum/academic institution collection accession numbering where the date of acquisition is given followed by the number of the item in relation to others preceding it that year. This inscription appears to have significant age and would suggest a possible date of 1886 (or earlier) for the current lot. If this is the case then the mechanism may have some historic importance (from a technological point of view) both with regards to the development of the gyroscopic compass and early electric motors.
An early electric motorised gyroscope Unsigned, bearing a collection accession number suggesting a date of circa 1886 With heavy turned brass flywheel mounted on an arbor with pin pivots at each end and incorporating twin triangular section rotors set between a pair of horseshoe-shaped electromagnets with green silk insulated windings positioned within the inner ring of the dual-axis gimbal assembly, the whole mounted via hinge joint and ball-race rotation bearing onto a baluster-turned lignum vitae upright over large moulded mahogany disc base inscribed in white ink 1886-29 to leading edge, 37cm (14.5ins) high. Although the unusual properties of a rotating flywheel had been observed since ancient times the importance of the gyroscope as a potential navigational aid was first established by Leon Foucault in 1852. In that year he constructed apparatus which incorporated a gimballed gyroscope assembly (of the form that became relatively standard from that time onwards) in order to demonstrate the earth’s rotation; Foucault also coined the name for the apparatus based on the Greek word for rotation gyros. At around this time a very similar mechanism was independently devised by the German schoolteacher Friedrich Fessel. It was this apparatus which Charles Wheatstone chose to discuss in his 1864 essay entitled On Fessel’s gyroscope which was published in the Proceedings of the Royal Society of London, vol. 7, pages 43-48. The use of an electric motor to provide indefinite motion to a gyroscope is thought to have first been applied during the 1860’s. This advance lead to the potential practical application of the gyroscope as a heading indicator, with further subsequent development resulting in the first practicable gyroscopic compass being patented in 1904 by the German inventor Hermann Anschütz Kaempfe. It is perhaps appropriate to suggest that the current lot may have been made as a demonstration model to illustrate how a simple gyroscope can be made to seek True North by the addition of a pendulous weight applied to the gimble which imparts a precessional force as the Earth rotates underneath it, with the outcome that the gyro ends up aligning itself to the Earth's axis. The two pulleys at the top and bottom of the outer gimbal are believed to be for this purpose. The mechanism is particularly noteworthy in that it employs an unusual design of motor to drive the flywheel constructed with two horseshoe-shaped electromagnets facing each other with the space between occupied by the spin axis arbor of triangular section with rounded apexes. The lack of brushes and unusual profile of the arbor would suggest that drive is enabled via alternating magnetic attraction as the triangular rotor's gap with the stator changes. The presence of two pairs of opposing coils would indicate that the assembly would require a pulsed power supply which, during the late 19th century, could have been supplied by an alternator. When the design and proportions of the rotors are considered it is probable that the efficiency of the motor would be very low, however for the purpose of maintaining the motion of the gyroscope the small amount of torque provided would have probably been sufficient. The white ink numeric inscription to the base of the current lot conforms to museum/academic institution collection accession numbering where the date of acquisition is given followed by the number of the item in relation to others preceding it that year. This inscription appears to have significant age and would suggest a possible date of 1886 (or earlier) for the current lot. If this is the case then the mechanism may have some historic importance (from a technological point of view) both with regards to the development of the gyroscopic compass and early electric motors.
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.jpg "Source: Christie's")
.jpg "Source: Christie's")
