Reference numberMS/119/2/14
TitleFrist half of letter from Charles James Buchanan Riddell, Toronto to Humphrey Lloyd
Date27 July 1840
DescriptionRiddell thanks Lloyd for his letter, for sending silk and ordering a wet and dry thermometer. However, the damage to the old one has not affected the observations as one of the standard thermometers was covered in silk and registered in its room.

Riddell has recently received the small apparatus and discusses their usefulness. He notes the rings are especially invaluable for their temporary observatory where the magnets are affected by slightest movement. Benefits of the long scale. Discussion on the horizontal force telescope. Riddell discusses his letter to [Edward] Sabine regarding significant disturbance caused by an aurora on the term day of May. The registers arrived in Toronto a fortnight ago.

Riddell discusses his trials of temperature correction for the vertical force magnetometer. Lloyd has sent Riddell a new vertical force magnetometer. Riddell has concerns about the position of the new vertical force magnetometer in the observatory and that the force of the new one will be greater than the current instrument, that the azimuth and the interval of the pillars may be thrown out. Riddell discusses possible solutions for this.

Riddell notes the time of vibration of the magnets in Toronto compared with London, as requested by Lloyd, and discusses details of the observations. Discussion of the absolute total intensity at London and Toronto.

[The second half of this letter is MS/119/2/16]
Physical descriptionInk on paper
Access statusOpen
Related records in the catalogueMS/119/2/16
Fellows associated with this archive
NA7327Riddell; Charles James Buchanan (1817 - 1903)1817 - 1903
NA8252Lloyd; Humphrey (1800 - 1881)1800 - 1881
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