Reference numberMS/119/2/79
TitleLetter from Frederick Marow Eardley-Wilmot, Cape of Good Hope Observatory to Humphrey Lloyd, Trinity College, Dublin
Date31 March 1841
DescriptionEardley-Wilmot updates Lloyd on the proceedings at the Cape of Good Hope observatory. Eardley-Wilmot asks Lloyd for more information regarding the vertical force magnetometer, and the placement of the instrument has caused delays. Eardley-Wilmot describes the different positions he tried and the readings for deviation he obtained from the crosses, the confusion he is finding in interpreting the results. Eardley-Wilmot concludes the magnetic axis of the bar was nearly horizontal and would like to verify this point by repetition before the permanently fixing the instrument. However, he has been unable to get readings where the position of the bar was the same as what it had previously been. Eardley-Wilmot enquires how to obtain a satisfactory measurement of the half difference.

Discussion on readings made by the micrometer.

In Eardley-Wilmot’s bar the magnetic axis and the line joining the crosses differ coincidentally.

The horizontal force instrument decreases in power regularly. Discussion on the position of the vertical force instrument. Eardley-Wilmot informs Lloyd that he has fixed the vertical force in the magnetic meridian.
Physical descriptionInk on paper
Access statusOpen
Fellows associated with this archive
NA6061Eardley-Wilmot; Frederick Marow (1812 - 1877)1812 - 1877
NA8252Lloyd; Humphrey (1800 - 1881)1800 - 1881
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