BURCKHARDT, Johann Karl (1773 –1825), astronomer and mathematician. Autograph letter signed to James Hartly, one side on one page (once a bifolium), 8vo, 14 March 1820, informing him that he has “received this moment a message from Her Royal Highness the Duchess of Clarence to be with her by six oftc this evening. As such I shall not be able to be with you at the time appointed ……… I shall the moment I leave H.R.H proceed to Bridge Street”. Small repair to central stab hole.
Burckhardt was born in Leipzig, Germany, but settled in France, becoming naturalized as a French citizen in 1799 (from thereon using the name Jean Charles Burckhardt) and in 1807 became director of the observatory at the École militaire. Burckhardt is remembered in particular for his work in fundamental astronomy, and for his lunar theory, which was in widespread use for the construction of navigational ephemerides of the Moon (published in the Nautical Almanac from 1821 to 1861). (Wikipedia).
Adelaide, duchess of Clarence married William, duke of Clarence in 1818, and they passed the first year together in Hanover, where, in 1819 she bore a daughter who lived only a few hours. Their second child, the Princess Elizabeth Georgina Adelaide, born on 10 December 1820, died in the following year. Their principal English residence was Bushey Park, Middlesex, where they lived until the accession of William to the throne in 1830.