Royal Society. 139 



Actuated by these impressions, on the occasion of a letter ad- 

 dressed by Baron Von Humboldt to His Royal Highness the Duke of 

 Sussex, P.R.S*., the Council of this Society, on April 13, 1837, re- 

 solved to apply to Government for aid in prosecuting, in conjunction 

 with the German Magnetic Association, a series of simultaneous ob- 

 servations ; and in consequence of an application founded on such 

 their resolution, a grant of money was obtained for the purchase of 

 instruments for that purpose. By reason, however, of the details 

 and manipulations of the methods then recently introduced into 

 magnetic observations by Gauss being at that time neither com- 

 pletely perfected, nor their superiority over the old methods fully 

 established by general practice, the precise apparatus to be employed 

 in these operations was not at the time agreed upon, and was still 

 under discussion, subject to the report of the Astronomer Royal on 

 the performance of an instrument on Gauss's principle established at 

 Greenwich, at the lime when the subject in its present more ex- 

 tended form was referred by the Council to this Joint Committee, so 

 that the grant in question has not, in point of fact, been employed 

 or called for. The Committee consider tliis as in some respects for- 

 tunate, as in consequence of the delay time has been given for a 

 much maturer consideration of the whole subject ; and should it now 

 be taken up as a matter of public concern, they consider that it will 

 be necessary to provide for a more continuous and systematic series 

 of observations, by observers regularly appointed for the purpose, 

 and provided with instruments and means considerably more costly 

 than those contemplated on the occasion in question. 



On the general advisableness of calling for public assistance in 

 the prosecution of the extensive subject of terrestrial magnetism, in 

 both the modes referred to them for their consideration, (viz. by 

 magnetic observatories established at several stations properly se- 

 lected on land, and by a naval expedition expressly directed to such 

 observations in the Antarctic Seas,) your Committee are fully agreed. 

 They consider the subject to have now attained a degree of theo- 

 retical as well as of practical importance, and to afford a scope for 

 the application of exact inquiry which it has never before enjoyed, 

 and which are such as fully to justify its recommendation by the 

 Royal Society to a revival of that national support to which we are 

 indebted for the first chart of variations constructed by our illustrious 

 countryman Halley in a.d. 1701, on the basis of observations col- 

 lected in a voyage of discovery expressly equipped for that purjiose 

 by the British Government. 



As regards the first branch of the question referred to their con- 

 sideration, they are of opinion that the stations which have been 

 suggested to them, viz. Canada, St, Helena, the Cape, Van Diemen's 

 Land, and Ceylon (or Madras), are well selected, and perhaps as nu- 

 merous as they could venture to recommend, considering the expense 

 which would require to be incurred at each, and that in each of 



* A translation of Baron Von Humboldt's letter was given in Loud, and 

 Edinb. Thil. Mag, vol. ix. p. 42.— Edit. 



