Reference numberMS/119/2/66
TitleLetter from Charles James Buchanan Riddell, Woolwich to Humphrey Lloyd
Date11 November 1845
DescriptionRiddell discusses fixing iron bars of the induction inclinometer with their permanent poles reversed so that the effect of their permanent magnetism may be counterbalanced. Discussion on the practical directions in Riddell’s instructions written for the one bar instruments and determining the temperature correction of the bars belonging to instruments in Bermuda. Determining temperature corrections, it is desirable that the two bars shall be in the same position relative to the suspended magnets.

Correcting the portable instructions.

Riddell has not heard anything from the East India Company about ordering new instruments.

Riddell discusses [Edward] Sabine’s pamphlet regarding the description of the theodolite magnetometer and requests Lloyd to send him a copy.

The Board of Ordnance have determined the further continuation of the observations after 31st December.

Riddell is currently examining the azimuth of the diurnal variation of the dip obtained from the observation of the induction inclinometer from the horizontal force and vertical force. Discussion on the comparison between solid iron bars and the hollow ones on the amount of magnetism. Riddell asks if the hollow bars should have an inner bar added.
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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