40 REPORT — 1841. 



meridian of which had been indicated by the daily observations in the pass- 

 age from Kerguelen's Land to Van Diemen's Land, leaving only its latitude 

 undecided. Having accomplished this, they will proceed, as rapidly as cir- 

 cumstances will permit, to seek and determine the position of the point of 

 vertical dip. The observations at sea, it should be mentioned, succeed to the 

 fullest extent of the most sanguine expectations ; so much so, that the three 

 magnetic elements are daily observed on board, with a precision perfectly 

 adequate to the actual demands of magnetic science. 



Intimately connected with a system of simultaneous observations at central 

 stations, is the subject of magnetic surveys of the surrounding districts. It 

 is only by reference to such central stations as zero points, that itinerant de- 

 terminations can be divested of the influence of temporary and casual mag- 

 netic derangement, and brought into comparability with the general mag- 

 netic system of the globe. It is, therefore, of the utmost importance that 

 every advantage should be taken of the present fortunate conjuncture to secure 

 the ivhole benefit of the simultaneous system, and to extend it from points 

 over districts. Itinerant observations, made on a concerted system, and pre- 

 cisely simultaneous with those at the fixed observatories, will acquire (if accu- 

 rately made) all the value of stationary ones, becoming, ipso facto, and at 

 each instant, reducible to a central station. Moreover, by this means alone 

 can the amount of station-error for each element, at the central stations them- 

 selves, be ascertained ; by which is meant, all that part of each resolved ele- 

 ment of the magnetic force, which, not being participated in by the surround- 

 ing district, must be attributed to attractions merely local and accidental. 

 Without such surveys, executed at some epoch, this error cannot be even 

 approximately fixed. If executed at this particular time, not only will it be 

 settled with precision, but the surveys will become an integrant part of 

 the whole mass of observation, and be rendered infinitely more valuable as 

 data for future reference, than they could possibly be, if deferred till after 

 the conclusion of the stationary observations. 



Under this impression, it is highly gratifying to your Committee to be en- 

 abled to announce, that one very important survey of this kind — that of the 

 British possessions in North America — has, on the application of the Presi- 

 dent and Council of the Royal Society, been undertaken by Government, on 

 a scale both liberal and satisfactory — a young, ardent, and instructed officer, 

 Lieut. Younghusband, R.A., qualified for the work by a residence and prac- 

 tice in magnetic observation in the observatory at Toronto, having been added 

 to the establishment of that observatory, with a view to this especial ser- 

 vice, for three years, with a non-commissioned officer as his assistant, fur- 

 nished with every instrumental requisite, a liberal provision for travelling 

 expenses, and with the promise of gratuitous canoe conveyance, from the 

 Hudson's Bay Company, in the territories belonging to them. In anticipa- 

 tion, moreover, of a similar magnetic survey of South Africa, though as yet 

 no formal application for such a survey has been made, the Master-Gene- 

 ral of the Ordnance has ordered a second officer of Artillery (Lieut. Clerk) 

 to be attached to the observatory at the Cape of Good Hope. 



As regards this important department of the general subject, your Com- 

 mittee have further to notice the magnetic survey of British Guiana, which 

 has been undertaken by Mr. Schomburgk, one of the Commissioners appointed 

 by Government to determine the boundaries of that province, and who, on an 

 application to that effect on the part of the Royal Geographical Society, has 

 been supplied by your Committee, from the grants placed at their disposal, 

 with a transportable magnetometer (to be returned when the Avork is com- 

 plete) — the receipt of which is acknowledged by a letter from the Secretary 



