Lot Essay
A REMARKABLY FINE EXAMPLE OF A RARE EIGHTEENTH-CENTURY PORTUGUESE MARINER'S COMPASS. Developed in the 16th century, the azimuth compass was intended for use by seamen and incorporated sights which, through alignment with a celestial body, allowed the calculation of the variation between true and magnetic north. The instrument remained in use throughout the 17th and 18th centuries, and, by the 18th century, Portuguese instrument-makers were producing finely-decorated examples such as this.
The contemporary British scientist Gowin Knight noted the advantages of this type of needle over the shapes adopted by English makers at the time in his 1749 article: 'For, being made broad at the Ends, and slender in the Middle, its Weight is removed as for as possible from the Centre: On which account, if it once point true, the Friction at the Centre cannot be so easily be put in Motion; and its Vibrations, when in Motion, will be slower; so that their Limits may more nicely be observed'.
Although examples of this type of compass are found in institutional collections -- one by Ferreira in the Musée de la Marine, Paris and another by Joseph da Costa Miranda in the Whipple Museum, Cambridge (illustrated in Bennett) -- they are very rare at auction.
The contemporary British scientist Gowin Knight noted the advantages of this type of needle over the shapes adopted by English makers at the time in his 1749 article: 'For, being made broad at the Ends, and slender in the Middle, its Weight is removed as for as possible from the Centre: On which account, if it once point true, the Friction at the Centre cannot be so easily be put in Motion; and its Vibrations, when in Motion, will be slower; so that their Limits may more nicely be observed'.
Although examples of this type of compass are found in institutional collections -- one by Ferreira in the Musée de la Marine, Paris and another by Joseph da Costa Miranda in the Whipple Museum, Cambridge (illustrated in Bennett) -- they are very rare at auction.