NATURAL PHILOSOPHY. 131 



evening, judging by the effect on the wires at that time, and I do not 

 recollect that I have ever been mistaken in my predictions. 



Thursday, April 22, 1852, were much troubled by an atmospheric 

 current; sometimes preventing our working for half an hour or 

 more, and then disappearing for about that time ; the current was 

 constantly changing during the whole evening. We had a very bril- 

 liant display of the Aurora. 



The Aurora Borealis seems to be composed of a vast mass of elec- 

 tric matter, resembling in every respect that generated by the electro- 

 galvanic battery ; the currents from it change, coming on the wires, 

 and then disappearing as the mass of the Aurora rolls from the ho- 

 rizon to the zenith sometimes so faintly as to be scarcely percepti- 

 ble, and then so strongly as to emit one continual blaze of fire yet 

 very different from what we commonly term atmospheric electricity, 

 and which we cannot relieve ourselves from, as in the latter case, by 

 placing ground wire conductors in close proximity to the line wires. 



TERRESTRIAL MAGNETISM. 



No one has contributed more to the progress of Terrestrial Mag- 

 netism during the last few years than Col. Sabine, formerly Presi- 

 dent of the British Association. Heretofore we owed theories on this 

 subject much more to the boldness of ignorance than to the just confi- 

 dence of knowledge ; but from the commencement of the systematic 

 observations which Col. Sabine has been so active in promoting, this 

 vague and useless theorizing ceased, to be succeeded ere long by 

 the sound speculative researches of those who may be capable of grap- 

 pling with the real difficulties of the subject, when the true laws of 

 the phenomena shall have been determined. These laws are coming 

 forth with beautiful precision from the reductions which Col. Sabine 

 is now making of the numerous observations taken at the different 

 magnetic stations. In his address before the Association, in 1852, he 

 stated that the secular change of the magnetic forces was confirmed 

 by these recent observations'; and also that periodical variations de- 

 pending on the solar day and on the time of the year, had been dis- 

 tinctly made out, indicating the sun as the cause of these variations. 

 During the past year the results of the reductions of the observations 

 made at Toronto have brought out with equal perspicuity, a varia- 

 tion in the direction of the magnetic needle, going through all its 

 changes exactlv in each lunar dav. These results with reference to 



o *" */ 



the sun, prove the immediate and direct exercise of a magnetic influ- 

 ence emanating from that luminary ; and also the same conclusion 

 with regard to the influence of the moon. It would seem, therefore, 

 that some of the curious phenomena of magnetism which have hitherto 

 been regarded as strictly terrestrial, are really due to solar and lunar, 

 as much as to terrestrial magnetism. It is beautiful to trace with such 

 precision these delicate influences of bodies so distant, producing phe- 

 nomena scarcely less striking either to the imagination or to the philo- 

 sophic mind, than more obvious phenomena which originate in the 



