He observes that the earth for months prior to the afore-named disturbances “must have been in a state of electricity ready for that particular vibration in which electrification exists”; that all the vegetation had been “uncommonly forward ... and electricity is well known to quicken vegetation”; that the aurora borealis had been very frequent about the same time and had been twice repeated just before the earthquake, “of such colours as had never been seen before,” there being, one evening, “a deep red aurora borealis covering the cope of heaven very terrible to behold”; that the whole year had been “remarkable for fire-balls, thunder, lightning and coruscations, almost throughout all England,” all which “are rightly judged to proceed from the electrical state of the atmosphere”; and, finally, that, a little before the earthquake, “a large and black cloud suddenly covered the atmosphere, which probably occasioned the shock by the discharge of a shower.” He adds that, according to Dr. Childrey, earthquakes are always preceded by rain and sudden tempests of rain in times of great drought. Dr. Stephen Hales (1677–1761), who was Stukeley’s classmate at Bennet College, Cambridge, and later his chief assistant in the study of the natural sciences, and who afterward became celebrated for his physical investigations and discoveries, arrives at a like conclusion. He thinks that “the electric appearances were only occasioned by the great agitation which the electric fluid was put into by the shock of so great a mass of the earth.” The great noise which attended the disturbance of March 8, 1749, he conjectured was “owing to the rushing or sudden expansion of the electric fluid at the top of St. Martin’s spire, where all the electric effluvia, which ascended along the large body of the tower, being strongly condensed, and accelerated at the point of the weathercock, as they rushed off made so much the louder expansive explosion.” It may be added here that Dr. Hales is the one who, at a previous date, had communicated to the Royal Society his observation of the fact that the electric spark proceeding from warm iron is of a bright, light colour, while that from warm copper is green, and the colour from a warm egg of a light yellow. In his opinion, these experiments appeared to argue that some particles of those different bodies are carried off in the electric flashes wherein those different colours are exhibited. For Stephen Hales, consult the _Phil. Trans._, Vol. XLV. p. 409, as well as the abridgments of Hutton, Vol. IX. p. 534, and for his portrait see “Essays in Historical Chemistry,” by T. E. Thorpe, London, 1894. For Stukeley and for Stephen Hales: consult “General Biographical Dictionary,” Alex. Chalmers, London, 1814, Vol. XVII. pp. 41–43.