232 Report on Terrestrial Magnetism. [July 



northern magnetic poles of convergence and verticity, whether these 

 poles are tw o different points, or one and the same ; indeed, continued 

 observations at such stations would go far to decide this question, 

 highly important in a theoretical point of view. M. de Humboldt has 

 mentioned Quebec as a desirable station. To this place, and also to 

 Montreal, we conceive that an objection exists, of which possibly M. 

 de Humboldt is not aware ; many of the houses in those cities are roof- 

 ed with tinned iron. This objection may not, how r ever, exist in some 

 of the establishments in the vicinity of either of these cities. "We con- 

 sider that i lie most advantageous positions would be, one near the 

 most northerly establishments in Hudson's Bay, and another at or 

 near to Fort Resolution on Great Slave Lake. As, however, observers 

 in such positions would be placed almost beyond the pale of civilizati- 

 on, we fear that, for some time at least, it would be found quite im- 

 pracin aide to obtain regular observations at these important stations. 

 It w ould likewise be desirable that there should be a station in Nova 

 Scotia or New foundland; the latter would be the preferable position. 



If the government of the United States were to give their cordial 

 co-operaiion to M. de Humboldt's plan, by the establishment of three 

 or more permanent magnetical observatories, in different longitudes, 

 these, with what we may expect to be undertaken by Russia in the 

 extreme north-west, and our own establishments, would afford the 

 means of obtaining a mass of more interesting magnetical observations 

 than could perhaps be derived from any other portion of the earth's 

 surface. 



M. de Humboldt mentions New Holland, Ceylon, the Mauritius, the 

 Cape of Good Hope, Si. Helena, and a point on the east coast of South 

 America, as desirable stations, and we fully concur in the propriety of 

 the selection. Although Van Diemen's Land, from its greater proxi- 

 mity to the southern magnetic pole, would be a more advantageous 

 position for magnetical observations than Paramatta, yet the circum- 

 stance alone of there being an astronomical observatory established 

 at Paramatta, renders it peculiarly adapted for a magnetical station. 

 Possibly circumstances may hereafter admit of magnetical observations 

 being also made at Hobart Town, in conformity with the general plan 

 which may be adopted. 



The Island of Ascension, from its proximity to the magnetic equa- 

 tor, would possess peculiar advantages for a magnetical station ; but 

 these must, in a great degree, be counterbalanced by the nature of its 

 soil, which, being wholly volcanic, would exert an influence on the 

 needle that would render observations made there of a doubtful cha- 

 racter ; indeed, the same objection applies to St. Helena and most of 

 the islands of the Atlantic. Some recent observations, those of Lieut. 

 Allen, R. N., in the expedition up the Niger, would point to the 



