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XV.—Results of the Makerstoun Observations, No. II. On the Relation of the Varitions of the Vertical Component of the Earth's Magnetic Intensity to the Solar and Lunar Periods

Published online by Cambridge University Press:  17 January 2013

J. Allan Broun Esq.
Affiliation:
Director of General Sir T. M. Brisbane's Magnetical and Meteorological Observatory.

Extract

The following results are deduced from the observations of the balance or vertical force magnetometer, which consists of a magnetic needle, balanced horizontally, and resting, by a knife-edged axle, on agate planes. Much doubt has been entertained as to this instrument's capability of shewing changes of moderate nicety, and it has been considered altogether unavailable for changes of long period: it has been shewn (Vol. XVI., p. 67), that there are several difficulties in the way of an accurate interpretation of the observations, independent of the instrumental capacity. If it be added, that disturbances seem to affect the daily means of the vertical component, in a more serious way than they do those of the horizontal component, it will be seen that there are a series of difficulties, which tend to render good and consistent results from the balance magnetometer nearly unattainable. It will be judged afterwards how far these difficulties have been overcome in the present instance.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1846

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References

page 137 note * Revised instructions by a Committee of the Royal Society of London, p. 37.

page 137 note † I shall generally use the terms vertical or horizontal component, instead of vertical or horizontal force; the latter are not at all expressive where the changes may be altogether due to variations of dip.

page 139 note * Toronto Observations for 1840, 1841, and 1842. Abstracts, &c., p. lx. The Toronto observations were made every two hours, and the Makerstoun observations every hour.

page 141 note * Reference to Results of the Makerstoun Observations, No. I., p. 99 of this volume.

page 141 note † Introduction to the Makerstoun Observations for 1843.

page 144 note * Each of these days was actually observed (observations were made) at the time as a day of disturbance.