146 Magnetic Disturbance on September 25th and 26th, ISll. 



A chart, showing more plainly the discoveries and track of the expe- 

 dition, is herewith transmitted ; and a more detailed plan, containing 

 all magnetic determinations, shall be sent as soon as they are reduced. 



I have much satisfaction in being able to add that the service has 

 been accomplished without the occurrence of any casualty, calamity, 

 or disease of any kind, and there is not a single individual in either 

 of the ships on the sick-list. 



It affords me the highest gratification to acquaint you, that I have 

 received the most cordial and efficient co-operation from my well-tried 

 friend and colleague Commander Crozier, of the Terror, and no terms 

 of admiration that I can employ can do justice to his great merit; nor 

 have the zeal and persevering devotion of the officers of both ships been 

 less conspicuous, under circumstances of no ordinary trial and diffi- 

 culty; and whilst the conduct of our crews has been such as to reflect 

 the highest honour on their characters as British sailors, it has given 

 to myself. Commander Crozier, and the officers of the expedition, the 

 most confident assurance of more extended success in pursuing the im- 

 portant duties we have yet to fulfil. 



H.M.S. Erebus, Van Dienien's Land, April 7, 1841. 



XXIV. Observations made at the Magnetic Observatory at Toronto, 

 during a remarkable Magnetic Disturbance on the 25th and 16th of 

 September, 1841 ; with Postscripts, containing the Observations of the 

 same Disturbance made at the Magnetic Observatories of Trevan- 

 drum, St. Helena, and the Cape of Good Hope^. 



([llustrated by Plate I.) 

 nPHE interest which Mr. Airy's Circular Letter has excited on the subject of 

 ^ the niagnetical disturbance, which was observed at Greenwich on the 25th 

 of September last, makes it probable that considerable advantage luay be 

 derived, bj" immediate publicity being given to the observations which were 

 made on the same day at the Magnetical Observatory at Toronto in Canada, 

 showing the effects of the same disturbance in America. 



In the regular course of the publication, proceeding under the direction 

 and at the expense of Government, of the olaservations made at the I\Iagne- 

 tical Observatories conducted by officers of the Royal Artillery, several months 

 would necessarily elapse before the observations of September 25, 1841, would 

 pass through the press. Under these circumstances, the Master-General 

 of the Ordnance has approved of their immediate publication in a separate 

 form, Mhich will enable them to be communicated at once to the Directors 

 of similar establishments in all parts of the globe ; and the Committee of the 

 British Association, appointed to conduct the co-operation of that body in 

 the system of simultaneous niagnetical and meteorological observations, have 

 deemed this a fitting occasion for the employment of a portion of the grant 

 placed at their disposal. 



The abstracts received from the Observatory contain the observations ex- 



* Reprinted, by the kiud permission of Lieut.-Col. Sabine, from the original publication, 

 recently i)rinted and circulated at tlic expense of the British Association (to whose forth- 

 coming Reiiort for 1811 it will be a])pendcd), with the approbation of the Master-General of 

 the Ordnance. Mr. Aire's Circular Letter has already appeared, in our last Supplement, vol. 

 xix. p. 505. We are enabled to add, on the autliority of Prof. Dove, in a letter addressed to 

 Mr. II. Croft, that at Berlin, " on the 25th of September, the magnetic needle was observed 

 both iu the morning and at noon, and that no considerable perturbation was visible." 



