HISTORY OF THE ATOMIC THEOET. 25 



known to be magnetic, and consequently, that there exists in 

 the higher regions of the atmosphere an elastic fluid partaking 

 of the properties of iron, or rather of magnetic steel, and 

 that this fluid, doubtless from its magnetic property, assumes 

 the form of cylindric beams. It should seem, too, that the 

 rainbow-like arches are a sort of rings of the same fluid, 

 which encompass the earth's northern magnetic pole, like as 

 the parallels of latitude do the other poles ; and that the beams 

 are arrayed in equidistant rows round the same pole. ♦ * • 

 Things being thus stated, I moreover suppose that this 

 elastic fluid of magnetic matter is, like vapourized air, an 

 imperfect conductor of electricity; and that when the equi- 

 librium of electricity in the higher regions of the atmosphere 

 is disturbed, I conceive that it takes these beams and rings as 

 conductors, and runs along from one quarter of the heavens 

 to another, exhibiting all the phenomena of the aurora 

 borealisJ* * 



In the edition of 1834 he still adheres to the same theory ; 

 some will look on it as absurd ; it is certainly the result of 

 great daring, or in other words, it may be viewed as the rea- 

 soning of a man who has exhausted all his knowledge in 

 finding a cause, feels certain that there is one, and decides 

 upon that which is most conformable to his knowledge, with- 

 out waiting for a wider view, or for a time when something 

 perfectly nevv might entirely change the scene. 



This essay on the aurora he considered as of great import- 

 ance. He begins with these words ; " As this essay contains an 

 original discovery which seems to open a new field of inquiry 

 in philosophy, or rather, perhaps, to extend the bounds of one 

 that has been as yet but just opened ; it may not, perhaps, be 

 unacceptable to many readers to state briefly the train of 

 circumstances which led the author to the important con- 

 clusions contained in the following pages." And yet we take 

 up treatises on the aurora, and do not even find Dalton's name 



♦ The pages refer to the new edition. 

 E 



