IV. On the height of the aurora borealis

• Published in: Proceedings of the Royal Society of London
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 1880
• Subjects: aurora borealis
• Online Access: http://dx.doi.org/10.1098/rspl.1879.0128; https://royalsocietypublishing.org/doi/pdf/10.1098/rspl.1879.0128

Our experiments on the electric discharge, which have been already published in the “Phil. Trans.” and the “Proceedings of the Royal Society,” enable us to state with some degree of probability the height of the Aurora Borealis, when its display is of maximum brilliancy, and also the height at which this phenomenon could not occur on account of the great tenuity of the atmosphere. In Part III of our electric researches, “Phil. Trans.,” p. 159, vol. 171, we have shown that the least resistance to the discharge in hydrogen is at a pressure of 0·642 millim., 845 M; after this degree of exhaustion has been reached, a further reduction of pressure rapidly increases the resistance. When the exhaustion has reached 0·002 millim., 3 M, the discharge only just passes with a potential of 11,000 chloride of silver cells (11,330 volts) at the highest exhaust we have been able to obtain (and which we believe has not been surpassed), namely, 0·000055 millim., 0·066 M, not only did 11,000 cells fail to produce a discharge, but even a 1-inch spark from an induction coil could not do so.