Lot Essay
This is one of the most complex chronometer balances ever designed and made; access to certain of the complicated adjusting screws is obtainable only through specially drilled holes made in the bimetallic balance rim.
Between June and September 1842 it was the subject of correspondence between its designer, Barraud & Lund, and the then Astronomer Royal G.B. Airy - (RGO 6/585:336-344). This resulted in Barraud & Lund being granted an appointment with Airy at the Royal Observatory on Monday morning 12 September 1842 when they took with them a colour-wash drawing; op. cit., of the balance annotated with their explanation of its various complicated adjustments.
In their initial letter dated 20 June 1842 Barraud & Lund explained that their reason for approaching the Astronomer Royal with their invention (sic) was prompted "by the receipt of a pamphlet this morning in which you have already given the subject (changes in rates of chronometers under extremes of temperature) much attention". The pamphlet to which they refer is undoubtedly the Account of Improvements in Chronometers made by R. John Sweetman Eiffe, with an appendix containing Mr Robert Molyneux's Specification of a Patent for Improvements in Chronometers. This was published by Order of the Lords Commissioners of the Admiralty in 1842, its Introduction having been written by Airy who arranged for its general distribution to chronometer makers.
The complex balance now fitted to Barraud No. 1724 conforms to the general design of the one illustrated (RGO 6/585:344) annotated "From Barraud & Lund. Received 1842 Sept 12 G.B. Airy". A further drawing (RGO 6/585:343) was submitted to the Astronomer Royal; it is signed BARRAUDS & LUND 41 Cornhill LONDON Novr 1842 and is annotated "From Msr Barraud & Lund 1842 Nov 7 G.B. Airy". It is not known whether any other examples of this balance are extant; the likelihood is that this is the only one and may have been taken by Barraud & Lund to the Royal Observatory when they had their meeting with the Astronomer Royal referred to above. It has now been fitted in Barraud No 1724 of circa 1840, the movement of which was lacking a balance.
BARRAUD'S "PATENT CORRECTING WEIGHTS"
Although Gould, op. cit., discusses and illustrates (illustration 78) the design and modus operandi of the much smaller and comparatively rare circular heat compensation weights fitted to the balance rim of an extremely limited number of Barraud chronometers, and which are referred to as "Barraud's Patent Correcting Weights", his very erudite work makes no reference per se to this class of balance now fitted in No. 1724. Similarly Cedric Jagger, op. cit., when also referring to the Patent Correcting Weights comments "in (their) original form, the correction was to have been applied as an attachment to the crossbar of the balance"; it would appear that this contention is supported by the reproduction (fig. 12) of the drawing (RGO 6/585:343) referred to above and which Barraud & Lund supplied to the Astronomer Royal in 1842.
Between June and September 1842 it was the subject of correspondence between its designer, Barraud & Lund, and the then Astronomer Royal G.B. Airy - (RGO 6/585:336-344). This resulted in Barraud & Lund being granted an appointment with Airy at the Royal Observatory on Monday morning 12 September 1842 when they took with them a colour-wash drawing; op. cit., of the balance annotated with their explanation of its various complicated adjustments.
In their initial letter dated 20 June 1842 Barraud & Lund explained that their reason for approaching the Astronomer Royal with their invention (sic) was prompted "by the receipt of a pamphlet this morning in which you have already given the subject (changes in rates of chronometers under extremes of temperature) much attention". The pamphlet to which they refer is undoubtedly the Account of Improvements in Chronometers made by R. John Sweetman Eiffe, with an appendix containing Mr Robert Molyneux's Specification of a Patent for Improvements in Chronometers. This was published by Order of the Lords Commissioners of the Admiralty in 1842, its Introduction having been written by Airy who arranged for its general distribution to chronometer makers.
The complex balance now fitted to Barraud No. 1724 conforms to the general design of the one illustrated (RGO 6/585:344) annotated "From Barraud & Lund. Received 1842 Sept 12 G.B. Airy". A further drawing (RGO 6/585:343) was submitted to the Astronomer Royal; it is signed BARRAUDS & LUND 41 Cornhill LONDON Novr 1842 and is annotated "From Msr Barraud & Lund 1842 Nov 7 G.B. Airy". It is not known whether any other examples of this balance are extant; the likelihood is that this is the only one and may have been taken by Barraud & Lund to the Royal Observatory when they had their meeting with the Astronomer Royal referred to above. It has now been fitted in Barraud No 1724 of circa 1840, the movement of which was lacking a balance.
BARRAUD'S "PATENT CORRECTING WEIGHTS"
Although Gould, op. cit., discusses and illustrates (illustration 78) the design and modus operandi of the much smaller and comparatively rare circular heat compensation weights fitted to the balance rim of an extremely limited number of Barraud chronometers, and which are referred to as "Barraud's Patent Correcting Weights", his very erudite work makes no reference per se to this class of balance now fitted in No. 1724. Similarly Cedric Jagger, op. cit., when also referring to the Patent Correcting Weights comments "in (their) original form, the correction was to have been applied as an attachment to the crossbar of the balance"; it would appear that this contention is supported by the reproduction (fig. 12) of the drawing (RGO 6/585:343) referred to above and which Barraud & Lund supplied to the Astronomer Royal in 1842.