Reference numberMS/119/2/10
TitleLetter from Charles James Buchanan, Toronto to Humphrey Lloyd, Trinity College, Dublin
Date2 April 1840
DescriptionRiddell thanks Lloyd for two letters dated 28th and 30th December. Riddell apologises to Lloyd that he cannot find the experiments of vibration with Lloyd’s declination magnet.

Riddell discusses the cooperation attained with other observatories and individuals across the globe. Riddell thanks Lloyd for the new scale mirrors and rings. Discussion on altering the position of the copper rings.

Riddell received [Edward] Sabine’s approval, regarding the site of the observatory and the course Riddell has taken, along with a programme of the times of observations.

Discussion on instructions received by [Sabine]. Riddell the formulas for the vertical force magnet and the abandonment of the adjustments of the centre of gravity of the magnetic axis. Riddell readjusted the vertical force instrument in time for the term day but experienced some difficulties.

The building of the Toronto observatory is to be commenced today, and the builder expects to finish the building in three months. The only delay is with the masonry, which will begin when weather conditions allow.

One of Riddell’s officers has made him another magnetometer which will be useful in all absolute measurements, and prevents Riddell having to move any of the instruments until the observatory is ready to receive them. To reduce the error of not having accurately divided the torsion circle Riddell has made the pillars eight or ten inches high.

Riddell hopes that four months of observations from Toronto can make up the general returns. Riddell has never been able to move the vertical force instrument, without some alteration in its readings. Therefore Riddell would like to accurately determine its effect on the time of vibration.
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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