Reference numberMS/119/2/61
TitleLetter from Charles James Buchanan Riddell, Woolwich to Humphrey Lloyd
Date17 July 1845
DescriptionRiddell informs Lloyd that he is winding up his magnetic affairs, and he may be required at military duty due to the calls in New Zealand. Riddell suggests ordering new unifilar magnetometers for each observatory for the purpose of absolute measurement, as the instruments currently used are inclinometer construction.

Riddell suggests sending larger instruments with eight and a half or nine inch circles divided to either five or ten inches. Riddell expresses doubts regarding the firmness of the divisions. Discussion on [William James] Smythe’s (at the St Helena observatory) suggestion to not mark the deflecting magnet itself.

Discussion on the induction inclinometers at the Indian observatories.

In Riddell’s opinion there are no other instruments that their observatories would want, with exception to the unifilar and an improved dip circle. Discussion on the portable unifilar.
Physical descriptionInk on paper
Access statusOpen
Fellows associated with this archive
NA7327Riddell; Charles James Buchanan (1817 - 1903)1817 - 1903
NA8252Lloyd; Humphrey (1800 - 1881)1800 - 1881
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