Reference numberMS/119/2/142
TitleLetter from John Allan Broun, 9 Abercorn Place, London to Humphrey Lloyd
Date21 December 1877
DescriptionBroun comments on the differences in results obtained by Lloyd at the Dublin observatory and Broun at the Makerstoun observatory and the problems this causes. Broun discusses his methods and experiments in order to solve this issue.

Broun informs Lloyd that he received an allowance of £150 from the government this year, and notes £4000 is needed to correct magnetic observations and get accurate results from them. Broun discusses results obtained by Lloyd. Broun notes Lloyd found the temperature and coefficient for the Dublin bifilar magnetometer. Broun notes that the annual law found by Lloyd at the Dublin observatories differs from that deduced by him at the Makerstoun and Toronto observatories, therefore before any progress can be made the cause of this difference must be discovered and eliminated. Broun informs Lloyd that he has now discovered the cause of this difference and describes the conclusions that he has come to. Discussion regarding the temperature coefficient for the bifilar magnet. Broun discusses the determinations of q by comparisons of the bifilar daily means. Discussion on the steps Broun took in order to obtain accurate results from the Dublin and Makerstoun bifilars, using the unit coefficients. Broun was able to use Lloyds deflection experiments from May 1847.

Broun concludes that the coefficients employed at Dublin and Makerstoun observatories from bifilars go together, and the annual law is exactly the same. Broun comments this is proof of the accuracy of the coefficients.

Broun studied the diurnal law for different months in 1843 and discusses his opinions.

Broun praises the Dublin instrument.

The horizontal force varied throughout the years from 1842 to 1850 in the British Isles. Broun expresses his regret that the Dublin observations were not continued in order to preserve accurate accounts of its changes.
Physical descriptionInk on paper
Access statusOpen
Fellows associated with this archive
NA3813Broun; John Allan (1817 - 1879)1817 - 1879
NA8252Lloyd; Humphrey (1800 - 1881)1800 - 1881
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