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Thomas Henderson

Thomas Henderson was a person of exceptional diligence, practical expertise, and mathematical ability - attributes that led to his appointment as the first Astronomer Royal for Scotland in 1834, and to a legacy of over 60,000 stellar measurements in that job, when he died suddenly 10 years later.

1 Hillside Crescent

Thomas Henderson's residence while Astronomer Royal for Scotland

Thomas was born in Dundee on 28 December 1798. His early life - in which he entered law, is described in the "The Early Years" menu item on the left.

In successive employments for the 12 years 1819 to 1831, while he was engaged in a legal career, early in this time he was acquainted with Professors Leslie and Wallace, Captain Basil Hall, and other distinguished persons.

Of interest is that although he was employed in a legal career he found the spare time to have a parallel, but unpaid, astronomical career. This was split between Edinburgh and London, as he was regularly in London on legal business. In Edinburgh he was afforded the facilities of the Astronomical Institute of Edinburgh on Calton Hill, working closely with Professor William Wallace (Professor of Mathematics at Edinburgh University) who was in charge of the instruments.

He first brought himself into notice as an astronomer in 1824, by communicating in that year to Dr Young, then Secretary of the Board of Longitude, a method of computing an observed occultation of a fixed star by the moon; of which that accomplished philosopher thought so highly, that he caused it to be published, under the title of an improvement on his own method, in the "Nautical Almanac" for 1827 and the four following years, accompanied in the last of those years by a second method, also proposed by Mr Henderson.

Dr Young was so impressed by Thomas Henderson that 2 weeks before he died (in 1829) he requested that Thomas be given his job as author of the "Nautical Almanac" when he died. Unfortunately, however, this job was given to John Pond, then Astronomer Royal at Greenwich.

Another publication which brought Mr Henderson into notice with astronomers was his detection of an error in the data furnished to Sir John Herschel for the determination of the difference in longitude of London and Paris. His paper was published in the Philosophical Transactions for 1827 and the Royal Society voted him a copy of the Greenwich Observations in return for his labour.

In 1828 he prepared an ephemeris for 1829, of the occultations of Aldebaran by the moon for 10 different observatories in Europe. In return for this and other valuable communications the Astronomical Society presented him with a copy of their Transactions, handsomely bound.

He was appointed to the Cape Observatory, by warrant, in South Africa in 1831, having not even applied for the position. He sailed to the Cape in January 1832, arriving in April. However, he was already suffering from health problems, which would ultimately lead to his premature death, and he cited these when resigning his post at the Cape in May 1833, whereupon he went to live in Edinburgh and analyse the data he had obtained at the Cape. His only remuneration at this point was a limited pension relating to his former life in the legal world.

In 1834 an agreement was concluded between the Government and the Astronomical Institute of Edinburgh, whereby the latter gave up to the University the use of their Observatory on Calton Hill which the former undertook to convert into a public establishment, by furnishing it with suitable instruments, and making provision for an observer and assistant.

Thomas Henderson was appointed on 18 August 1834 by Royal commission "to apply himself with diligence and zeal to making astronomical observations at the said observatory, for the extension and improvement of astronomy, geography, and navigation, and other branches of science connected therewith".

He read a paper on Alpha Centauri to the Society in January 1839. Although he was almost certainly the first person to successfully use parallax to measure the distance to a nearby star - Alpha Centauri - Bessel went into publication first and obtained that accolade. It was his care and attention to detail that prevented him from publishing his results before Bessel. Bessel, and the celebrated mathematician, Jacobi, visited him in 1842. He took them on a short tour of the Highlands.

He died of "Hypertrophy of the Heart" on 23 November 1846.

At his death 5 volumes of the "Edinburgh Astronomical Observations" had been published for 1834 to 1839. A sixth was almost complete. In the eyes of the Royal Astronomical Society the publications "not only do credit to the astronomer and his assistant, Mr Wallace, but have conferred on the observatory a high reputation among the similar institutions of Europe".

His Publications - some 70+ in number - are, in summary
a) In the Memoirs of the RAS - 28 papers
b) In the Monthly Notices of the RAS - 15 papers
c) In the Philosophical Transactions of the RS of London - 2 papers
d) In the Philosophical Magazine - 2 papers
e) In the London Quarterly Journal of Science - 7 papers
f) Ditto - New Series - 2 papers
g) In "Schumacher's Astronomische Nachrichten" - 11 papers
h) Plus 5 further publications
g) Plus the "Edinburgh Astronomical Observations" series.

Finally, it should be noted that in its Memoirs of Thomas Henderson, the Royal Astronomical Society described him thus - "an astronomer of first-rate merit, and one who, for many years, has been conspicuously distinguished among us by the frequency and importance of his contributions to our publications"

1 Hillside Crescent

Memorial on outside wall of the Royal Observatory, Calton Hill

Material for this page was generously supplied by the National Library of Scotland - http://www.nls.uk/