A NEW THEORY OF THE AURORA.

Dunstan Times, Issue 1051, 9 June 1882, Page 4

A NEW THEORY OF THE AURORA.

In a very able lecture by Professor W. Grylls Adams, recently published, we find the following theory propounded to account for the observed interrelation of earth currents, magnetic storms, aurora, and sunspots. Professor Adams assumes the sun to be a magnet, and infers that changes in his magnetism affect tho magnetism of the earth. Farther, the sun and moon, by dragging tho atmosphere towards them as the earth revolves, may cause that friction between earth and air, and also that evaporation which together may generate the sup. ply of positive clcctric't/ in the air and negative to the earth. “ Again, these tides in the atmosphere will cause the mass of it to lag behind the revolving solid earth, and at a height of 30 or 40 miles we have a layer of air which, for air, is a comparatively good conductor of electricity Here, then, we have, not a lagging of tho magnet behind the conductor, but a lagging of the conductor behind the magnet, and hence, according to the laws of Faraday, we may expect a current t r a gradual heaping up of electricily in the air in the opposite direction to the earth’s crust.” Thus the regular tidal waves in the atmosphere would cause the gradual transfer of positive electricity from the poles toward the equator either as a current or a mass of air statically charged. “ When the air is charged up to discharging point we may get the sudden discharges such as the aurora in the air and tho earth current in the earth ; and since the conducting layer of air approaches nearer to the earth in the colder polar regions, possibly within less than 20 miles of the earth’s surface, it may be found that tho discharge of the aurora may even take place from earth to air by gradual slow discharge, aided as it may he by the state of moisture of the air and by change of temperature and other causes.”