. Manual of the natural history, geology and physics of Greenland and the neighbouring regions / prepared for the use of the Arctic expedition of 1875, under the direction of the Arctic Committee of the Royal Society and edited by T. Rupert Jones. Together with Instructions suggested by the Arctic Committee of the Royal Society for the use of the expedition / published by authority of the Lords Commissioners of the Admiralty [microform]. Natural history; Scientific expeditions; Sciences naturelles; Expéditions scientifiques. *^**«W«teKtt«»a,»«,,,,^^ 704 TERRESTRIAL MAGNETISM. i|tf r. On Feb. 1
. Manual of the natural history, geology and physics of Greenland and the neighbouring regions / prepared for the use of the Arctic expedition of 1875, under the direction of the Arctic Committee of the Royal Society and edited by T. Rupert Jones. Together with Instructions suggested by the Arctic Committee of the Royal Society for the use of the expedition / published by authority of the Lords Commissioners of the Admiralty [microform]. Natural history; Scientific expeditions; Sciences naturelles; Expéditions scientifiques. *^**«W«teKtt«»a,»«,,,,^^ 704 TERRESTRIAL MAGNETISM. i|tf r. On Feb. 11, another of the term days, there was great dis- turbance of the magnetometer, but there seemed great doubt whether the aurora had any connexion with it. This was eight days after the sun had returned. [The results are recorded in divisions of the scale employed, and the reading 318 corresponds to tlie mean declination : on days when there were no remarkable disturbances, the change in the deflection was from 10 to 15 divisions of the scale. On Jan. 5, at 9 , the reading avus 298, and increased to 326 at , after which the change was 20 divisions in 5 minutes, and 16 more in the next 2 minutes to 362, then back to 315 in the next 2 minutes, and to 298 in the next 2 minutes. Again, on Feb. 11, from to 8, the changes in declination are from 298*57 to 213*40. For some hours the disturbances in both directions are very great. From lOh. to 13h. the change is from 210 to 360. Each division of the scale is equivalent to 2' • 2, so that this change of deflection amounts to 5° 30'. On Marcli 21, again, there are great disturbances at 18h. and 19h., but not so sudden nor so great as on the 11th of February; they are chiefly in the opposite direction.] *' The observers were troubled with cloudy weather, which often may have prevented them from seeing the aurora. Still it must be considered that the declination needle was not generally greatly distui'bed by the
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Keywords: ., bookcentury1800, bookdecade1870, books, booksubjectnaturalhistory
