CAUSE OF THE AURORA BOREALIS.

Patea Mail, Volume II, Issue 149, 13 September 1876, Page 2

CAUSE OF THE AURORA BOREALIS.

An interesting paper has just beeit read in the Academy of Sciences, from M,' Plante, describing experiments made by him with a flew to prove that the aurora borealis, is caused by electricity. To' this end he takes vessels, half-filled with 'salt water, into which he’introduces the electrodes of a. powerful battery ; the positive one digging deep into the water,and the negative one eilher above it, or shimmering the surface, or dipping arf inch or two into it. In the first case tve see its extremity is surrounded with luminous particles' forming a sort of garland; .in the second,- the water is depressed all round like a hollow homis-'

plicro, darting luminous rays all round; in the third case, the depression is still deeper, but jagged and. irregular, or waving' like a piece of cloth flagging in the wind, the phenomenon of fiery rags existing all round. M. Plante states that) owing to the salt water, the dominant colors of the rags are yellow, purple, and violet, similar to those of the aurora borealis (which, however, is more often rose-coloured or deep crimson in nature). In the two latter cases, where depressions arc made.in the water, the latter is.constantly tending to fill up the empty space; thus new radiations arc produced* closely imitating the darting of rays so characteristic of auroras. I’ho obscure circle or Segment caused in the latter by the haze or nebulous veil, that the electric stream encounters iri nature is represented in these experiments by the watery circle which surrounds the electrode, and around which the voltaic current expands. The water is violently agitated by the electric blast; whirlpools and luminous rings arc formed by the shocks of electrified waves against each other, and, if wo operate with but a small quantity of water, a luminous ebullition is finally generated, answering to the fluctuation of light that is also a characteristic of polar anrorasr