VI. On the anomaly in the variation of the magnetic needle as observed on ship-board

• Published in: Philosophical Transactions of the Royal Society of London
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 1819
• Subjects: Flinders; Bain; Spitzbergen
• Online Access: http://dx.doi.org/10.1098/rstl.1819.0008; https://royalsocietypublishing.org/doi/pdf/10.1098/rstl.1819.0008

The anomalies discovered in magnetical observations con­ducted on ship-board, were usually attributed to the imper­fection of the azimuth compass, until Captain Flinders, in his modest and enlightened paper on this subject, published in the Philosophical Transactions, suggested that they were probably owing to the concentration of the magnetic influence of the iron, made use of in the construction of the ship. The truth of this suggestion, and the accuracy of his observations, have since met with full confirmation, and his practical rules founded thereon have received additional support, from the “ Essay ” of Mr. Bain “ on the variation of the Compass,” published last year. As I have been materially anticipated by Mr. Bain, in a series of observations on the variation of the compass,* which I conducted on the coast of Spitzbergen, in the years 1815 and 1817, it will be unnecessary here to enter into the detail of these observations or enlarge upon the probable cause of the anomalies observed it may be sufficient to give a table of the most accurate of my observations, and annex to it the few general inferences which were drawn from it, during the voyage in which most of the observations were made, together with such remarks on each inference as seemed to me calculated for its elucidation. I shall, however, just premise, that I am not unconscious of the great liability to error in observations of this kind, and of the variety of causes (arising out of the unequal distribution of iron in different ships, whereby nu­merous local attractions are formed) which contribute to the multiplication of those errors: it is, therefore, with the greatest deference that I submit these deductions, particularly as I conceive it will require observations to be made under a vast variety of circumstances, and in many different vessels, be­fore correct and satisfactory conclusions can be drawn. It is only then as a step towards facilitating such general conclusions, the importance of which to our maritime concerns is so obvious, ...