Allen J Broun

John Allen Broun was the second Director in the Thiruvananthapuram observatory and he was also involved in setting up a museum and zoo in the city. From 1842- 1850 he was the director of an observatory in Makers Town in Scotland. From 1851 to 1856, he was the director of the Thiruvananthapuram observatory.

He shifted the focus of the institution from astronomy to meteorology and terrestrial magnetism. He set up a majestic observatory in Agastiyar peak which is around 6000 feet above sea level. His residence which is just behind the observatory building in Thiruvananthapuram is still in existence, though in a dilapidated state.

Broun seems to have been an excellent writer as it is evident from the following picturesque description of the on set of the monsoon quoteted in the Travancore manuel by Nagamayyah.

Allen Broun on Monsoon

The Royal Society President Sir Joseph Delton Hooker spoke on Broun’s contributions in November 30, 1878 as follows:

Address of Sir Joseph Dalton Hooker, C.B., K.C.S.I., The President,

Delivered at the Anniversary Meeting of the Royal Society, on Saturday, November 30, 1878.

Editor’s note: the printed pamphlet’s original page numbers are shown in brackets (5) to make it easier to cite this version, and the page breaks are shown with a thin red line. The original title page and its blank reverse had no numbers and the first page of text was numbered 3. The original footnotes are shown in the positions where they originally occurred.

A Royal Medal has been awarded to Mr. John Allan Broun for his investigations during thirty-five years in magnetism and meteorology, and for his improved methods of observation.

When the labours of Gauss had given an impetus to the study of terrestrial magnetism by rendering precision possible, Observatories devoted to this branch of research, in conjunction with meteorology, began to rise in various places. The late General Sir T.M. Brisbane erected one at Makers town, in Scotland, and placed it under the direction of Mr. Broun, who remained in charge of it from 1842 to 1850. His observations and their results, have been commended by Magneticians and meteorologists, for the skill employed in the development of new methods of reduction and investigation.

In 1851 Mr. Broun went to India to organize and take charge of a similar Observatory established at Trevandrum by His Highness the late Rajah of Travancore. Here he remained for thirteen years, accumulating results of very great value, then first installment of which, consisting of a volume on the magnetic declination, was published some years ago. Magneticians look eagerly towards the completion of this publication when the means necessary for the purposed shall have been furnished to Mr.Broun.

While in India he established an Observatory on a mountain peak 6,000 feet above the sea, and fitted it up with a very complete assortment of scientific instruments. This was an undertaking of a very arduous nature, affected in a wild country, and presenting great difficulties in the erection of instruments and obtaining trained observers.

Shortly after the commencement of magnetic observatories, Mr. Broun indicated the insufficiencies of the methods then in use for determining coefficients and correcting observations and he devised new methods for these ends, the principal of which have been generally adopted.

This is not the place in which to give a complete catalogue of Mr. Broun’s researches in magnetism and meteorology, extending as they do over a period of thirty-five years, but I may indicate those of his result’s that are of the greatest importance. Among them are the establishments of the annual laws of magnetic horizontal force, exhibiting maxima at the solstices and minima at the equinoxes. Mr. Broun was also the first to give in a complete form the laws of change of the solar-diurnal variation of magnetic declination near the equator, showing the extinction of the mean movement near the equinox. His researches on the lunar-diurnal variation of magnetic declination are of very great interest. Besides being an independent discoverer of the existence of this variation, he showed that near the equator its law in December was the opposite of that in June. He found, too, that the lunar-diurnal variation was in December sometimes greater than the solar-diurnal variation- that the lunar action.

was reserved at sunrise and that it was much greater during the day than during the night, whether the moon was above or below the horizon. Finally, he found that the lunar-diurnal law changed (like the solar-diurnal law at the equator) near the equinoxes, so that, as a consequence, the laws for the southern and northern hemispheres were of opposite natures.

Another and very remarkable fact discovered by Mr. Broun was that the variations from day to day of the earth’s daily mean horizontal force were nearly the same as the world over. He found certain oscillations in these daily means, which were due to the moon’s revolution, and others having a period of twenty-six days; the latter he considered as due to the sun’s rotation. It results from these investigations that the observed variations of the earth’s daily mean horizontal force have been represented with considerable accuracy in all their more marked features, by the combination of the means calculated for these different solar and lunar periods. During the discussion of these periods, Mr.Brouns found that the great magnetic disturbances were apparently due to actions preceding from particular points or meridians of the sun- a fact this (if verified) of very great importance.

In meteorology he has shown the apparent simultaneity of the changes of daily mean barometric pressure over a great part of the globe, and he has likewise discovered a barometric period of twenty-six days nearly. He was also the first to commence and carry out, during several years, a systematic series of observations of the motions of clouds at different heights ion the atmosphere; and, lastly, he has found certain laws connecting the motions of the atmosphere, and the directions of the lines of equal barometric pressure