The altitude of the aurora above the Earth's surface

Abstract

DALTON.—In the first edition of his Essays, pages 69 and 70, Dalton says that, from observations by himself at Kendal and by Crosthwaite at Keswick, distant 22 miles, at right angles to the observed arch, the altitudes of the edge of the arch being respectively 53° and 48°, the computed altitude by the parallax method was 150 English miles. An error of 2° in either altitude, which exceeds the bounds of probability, would give 83 or 750 miles respectively. In his preface he shows that his ideas of the aurora are original, although partly the same as those of previous authors. He finds that the beams of the aurora borealis are governed by the earth's magnetism, but notes that this idea had been conjectured by Mr. George Birbeck, of Settle, Yorkshire, and that it had also been more fully expounded by Halley.