Reference numberMS/119/2/52
TitleLetter from Charles James Buchanan Riddell, Woolwich to Humphrey Lloyd
Date14 February 1844
DescriptionIn Riddell’s opinion theodolite magnetometer is a good name and discusses his description of the instrument. Riddell informs Lloyd that he has now corrected the description of the induction inclinometer giving the description of the differential instruments, the additional apparatus and alterations required, the alterations required if the instrument is to be used in observations of absolute declination. Riddell intended to keep the circle the same as in the deflection magnetometer.

Riddell lists the instruments included in the instructions. Riddell suggests the deflection and theodolite magnetometers could be converted to an induction inclinometer if needed.

Riddell includes a description of the theodolite magnetometer as he intends to print in the instructions. Discussion on the construction of the instrument, the reading telescope and transit axis, the magnets to be made on the collimator principle.

According to [Samuel] Jones Lloyd does not wish for a transit axis for his instrument. Jones informed Riddell that a theodolite like Lloyd’s will cost £42.

Riddell will omit the description of Lloyd’s instrument as suggested by him. Riddell thinks the name declination and intensity apparatus is more suitable.

Riddell asks Lloyd about using two iron bars to make the permanent and induced magnetism act together in one bar and opposed in the other.
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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