Reference numberAP/12/15/6
TitleUnpublished letter, regarding southeast line of no variation from John Macdonald to Sir Humphry Davy
Date12 June 1826
DescriptionMacdonald discusses his desire to find the southeast line of no variation and the different locations for this line previously provided by various explorers. He then discusses possible relations between solar heat, polar attraction, and magnetism. Includes a diagram showing the locations of poles and magnetic meridians.

John Frederick William Herschel's initials appear in red ink next to the date received. An ink inscription at top of first page reads 'N. T.Y. [Thomas Young]'.

Subject: Geodesy

Written by Macdonald in Summerlands [Devon, England]. Received by the Royal Society on 15 November 1826.
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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