VI. On the influence of the ocean on the plumb-line in India

• Published in: Proceedings of the Royal Society of London
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 1859
• Subjects: General Earth and Planetary Sciences; General Environmental Science; South Pole; South pole
• Online Access: http://dx.doi.org/10.1098/rspl.1857.0114; https://royalsocietypublishing.org/doi/pdf/10.1098/rspl.1857.0114

This paper is a sequel to two former communications made to the Royal Society by the author. In the first of these (communicated in 1855), the deflection of the plumb-line caused by the mountain-mass north of Hindostan is calculated; and in the second (communicated in 1858), the effect of a small excess or defect of density prevailing through extensive parts of the earth’s mass, is found, with a view to determine whether any compensating cause can possibly exist below to counteract the large amount of deflection caused by the superficial mass lying above the sea-level. A survey of the causes of disturbance of the plumb-line cannot be complete without taking into consideration the influence of the ocean. To approximate to this is the object of the present paper. The author first adverts to the peculiar geographical position of Hindostan. The highest mountain-ground in the world lies to the north of it; and an unbroken expanse of ocean extends from its shores down to the neighbourhood of the South Pole. The excess of matter presented by the first causes a deflection of the plumb-line towards the north, decreasing in amount as we travel southwards. The deficiency of matter arising from the second causes a deflection of the plumb-line also towards the north, but decreasing in amount as we travel northwards. The consequence is, that while these two causes conspire to increase the deflection at the different stations, the action of the second tends to reduce in amount the errors which the mountain-attraction causes in the amplitudes.