| Description | Magnetic observations made during the British Antarctic Expedition of Captain Carsten Borchgrevink (also known as the Southern Cross Expedition ).
Records of vibration and deflection made by Louis Bernacchi, expedition physicist (24 observations), and William Colbeck, seamen (25 observations) using a Kew Observatory type unifilar magnetometer. These observations can be used to calculate the horizontal component of the earth's magnetic force and, in conjunction with measurements of declination, the strength of a magnetic field.
Volume contains:
One observation made at the Kew Observatory, Richmond , Surrey, England (presumably for callibration purposes). 14 April 1899
47 observations made at Cape Adare during the overwintering of the British Antarctic Expedition (also known as the Southern Cross Expedition). 3 August 1898 - 19 January 1900
One observation made at Hobart, Tasmania, Australia. 22 April 1900
Observations are made with varying frquency ranging from multiple observations a day to gaps of several days without observations.
Observations are hand written on printed sheets from the Kew Observatory marked 'K.O. Mag. Form A].' (for vibrations) or 'K.O. Mag. Form B.] (for declinations). Each printed sheet for vibrations has space to record:
Station, including latitude and longitude. Chronometer ID, error at station and daily rate. Magnet ID and constants. Effects of 90 degrees of torsion. Mean time at commencement and end. Semiarc of vibration at commencement and end. Temperature of magnet at commencement and end. Movements of the scale to the right and left with number of vibrations, time of passing centre wire and time for 50 vibrations.
This is followed by a set of pre-printed standard calculations with values added by hand. The reverse of some pages include additional calculations
There is a space for observation of torsion but this has not been used and a note states that a mean value has been applied in calculations.
Each printed sheet for deflections has space to record:
Station, including latitude and longitude. Mean time at station for commencement and end of observation. ID of deflecting and suspended magents and one division of scale. Distance in centimeters east and west. Temperature. Readings of verniers. Scale reading. Correction to middle of scale. Mean of verniers. Corrected circle reading. Means and difference. Observed angles of deflection.
This is followed by a set of pre-printed standard calculations with values added by hand. The reverse of some pages include additional calculations
Pasted into the front of the volume are certificates of examination for two centigrade thermometers and a loose certificate of examination for a unifilar magnetometer which also gives the constants and temperature corrections for the magnetometer. Certificates dated 1898, signed by Superintendent of the Kew Observatory, Charles Chree. |
| AdminHistory | For a full description of how to take measurements using the Kew Observatory pattern unifilar magnetometer see: https://theodora.com/encyclopedia/m/magnetometer.html |