Reference numberAP/12/15/3
TitleUnpublished letter, regarding magnetic variation from John Macdonald to Sir Humphry Davy
Date29 September 1825
DescriptionMacdonald writes about his research for a paper on magnetic variation to be published in the Encylopaedia Metropolitana, explaining that he had published previous papers on the topic and hoped to encourage others to carry out experiments in India, but that he had not yet received any new data. He writes about his theory relating to magnetic poles and diurnal variation. Includes a diagram illustrating magnetic variation in relation to the north pole.

Corrections appear throughout in ink.

Subject: Geodesy

Written by Macdonald in Summerlands, Exeter [Devon, England].
Physical descriptionInk on paper
Access statusOpen
Related records in the catalogueAP/12/15
Fellows associated with this archive
NA8200Davy; Sir; Humphry (1778 - 1829); chemist1778 - 1829
NA3036Macdonald; John (1759 - 1831)1759 - 1831
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