Reference numberMS/119/2/19
TitleLetter from Charles James Buchanan Riddell, Toronto to Humphrey Lloyd, Trinity College, Dublin
Date14 January 1841
DescriptionRiddell updates Lloyd on his health, and work conducted at the Toronto observatory. Discussion on the relative position of the magnet. Riddell asked Mr [William Cranch] Bond’s brother-in-law to send two magnets to be remagnetised. The two magnets sent by Lloyd arrived in November, discussion on their time of vibration with the stirrup. Riddell’s illness has prevented him from making any observations since the middle of November.

Riddell does not believe the corrections for the coefficient of horizontal force and vertical force magnetometers will be appreciable. Discussion on the constant correction to the readings of the declination. Riddell discusses his reasons for placing a weak magnet in the declination instrument. Riddell thanks Lloyd for ordering the long scales from [Thomas] Grubb.

Riddell will send Lloyd the details of the temperature correction observations. [Charles] Younghusband has taken a series of observations with one magnet. Discussion regarding the plan for the subterranean observatory at Munich.

Riddell discusses the temperature of the observatory. Discussion about the long scale of the declination. Since the occupation of the new observatory Riddell has been using Gauss’s scale and mirror for the horizontal force. Discussion regarding Riddell’s comments on the times of vibration of vertical force in the horizontal plane.

Riddell discusses his illness. His medical attendants recommend moving to the south for a change of climate. Younghusband has been living at the observatory and for the last two months and had complete superintendence of the observations. To get satisfactory results for the temperature correction Riddell was unable to take any absolute determinations.
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
Add to My Items

    Collection highlights

    Browse the records of some of our collections, which cover all branches of science and date from the 12th century onwards. These include the published works of Fellows of the Royal Society, personal papers of eminent scientists, letters and manuscripts sent to the Society or presented at meetings, and administrative records documenting the Society's activities since our foundation in 1660.

    The Royal Society

    The Royal Society is a Fellowship of many of
    the world's most eminent scientists and is the
    oldest scientific academy in continuous existence.
    Registered charity number 207043

    Website design ©CalmView


    + 44 207 451 2500
    (Lines open Mon-Fri, 9:00-17:00. Excludes bank holidays)

    6-9 Carlton House Terrace, London SW1Y 5AG

    Email Us →


    Subscribe to our newsletters to be updated with the
    latest news on innovation, events, articles and reports.

    Subscribe →

    © CalmView