James Francis Tennant

James Tennant is a redirect to this article. For other people, see James Tennent .

James Francis Tennant (born January 10, 1829 in Calcutta , † March 6, 1915 in England ) was a British geodesist, soldier, astronomer and government official.

Tennant was of Scottish descent and the eldest son of Sir James Tennant, Brigadier General of the Bengali Artillery, and his wife Elizabeth, née Pattinson. He attended private schools and the Addiscombe Military Academy, which he graduated with honors in mathematics. In March 1849 he took up service as a second lieutenant in the Bengali Engineer Corps in Calcutta.

Geodesic

Tennant was assigned to the Indian land survey and worked on the survey section between Sironj and Karachi . The arduous surveying work reached Karachi in May 1853. It was followed by a baseline survey in 1855 , for which Tennant carried out leveling work and determined the latitude of Karachi. During this time Tennant married Miss Augusta Dick, with whom he had three sons and a daughter. He was then assigned to other survey sections, where he held various managerial positions.

soldier

The Indian uprising of 1857 marked the end of his surveying work. Tennant served as an officer and was involved in the storming of the Lahore Gate during the reconquest of Delhi and later in the siege of Lucknow .

astronomer

After a short resumption of surveying work, Tennant (meanwhile in the rank of major) took over the directorate of the Madras Observatory for one year in 1859 , until he was replaced by Norman Robert Pogson . He worked for various building authorities in Burma , Bengal and Madras. After the death of his first wife in 1859, he married Selina Tudor Crawford in 1867, with whom he had three daughters.

In 1860, when a total solar eclipse was observed, it was confirmed that the protuberances visible at the edge of the moon during the eclipse had their origin on the sun (and not on the moon), and photographic images of the eclipse could be successfully obtained for the first time. In January 1867, Tennant pointed out that the upcoming solar eclipse of August 18, 1868 , the umbra of which would sweep the Indian peninsula, would allow the next step to decide whether the prominences would be removed

"Are gaseous or consist of solid particles, whether they shine in their own light or that of the sun, and even gather some information about their composition."

Tennant received support from the Astronomer Royal and the Indian government and, together with Lieutenant John Herschel and other officers, was able to observe the darkness from a station near Guntur . His attempt to photograph the corona was unsuccessful. However, he succeeded in observing a continuous spectrum of corona and emission lines in the spectrum of a protuberance. Polariscope observations by other members of his group showed that the corona is not self-luminous, but reflects the light from the sun's surface.

For the solar eclipse of December 12, 1871, the totality phase of which was also visible from India, Colonel Tennant again equipped an expedition with the support of the government, this time to Doddabetta in the Nilgiri Mountains . Under his direction spectroscopic observations were made and photographs of the corona were obtained.

In 1872 Sir George Airy asked Tennant to prepare observations in India of the Venus transit in 1874 . With the support of the British Association and Airy as the Astronomer Royal, Tennant again succeeded in obtaining instruments from the Indian government, on condition that they were then handed over to a solar observatory. Tennant watched the transit from Roorkee . Among other things, photographs of the event were again made. Tennant evaluated his observations and those of two other groups of observers and published the results in 1877.

Civil servant and retirement

On January 18, 1876, Colonel Tennant took over the management of the Royal Mint in Calcutta . He retired on February 6, 1882 and returned to England. He was admitted to the Advisory Board of the Royal Astronomical Society in 1885 and elected its President for the 1890/91 term.

His scientific publications deal mainly with geodetic topics and solar eclipses. In addition, he wrote articles on the optics of the mirror telescopes and other instrumental aspects and calculated some comet orbits.

Web links

• Obituary Notices: Fellows: - Tennant, James Francis. Monthly Notices of the Royal Astronomical Society, Vol. 76, p. 272 ​​(Obituary of the Royal Astronomical Society) ( bibcode : 1916MNRAS..76..272. )

• Portrait in the Science Photo Library

• Tennant JF: Total eclipses, and the total eclipse of 18th August, 1868. Calcutta Central Press Company Ltd., Calcutta 1868 ( digitized version )

• Tennant JF: Report on the preparations for, and observations of the transit of Venus, as seen at Roorkee and Lahore, on December 8. Office of the Superintendent of Government Printing, Calcutta 1877 ( digitized )

• Publications by JF Tennant in the Astrophysics Data System