A stick of dry sealing-wax was rubbed on the side of a dry wine-glass, and a cork ball, suspended as in the former experiments, played for some time between them: but glass rubbed with glass, or wax with wax, did not manifest any electric appearance. Whence it would appear, that in rubbing glass and wax together, the glass accumulated on its surface the identical æther that the wax lost. Nor is this a digression from my design: for if this opposition of the electricity of glass and wax be established, it still contributes to demonstrate the fallacy of Mr. Eeles’s experiments.
But what alone would intirely destroy this electric hypothesis, is, that from the experiments of Mr. Franklin and others, the clouds are sometimes found to be electrised _plus_, sometimes _minus_, and sometimes manifest no signs of electricity at all. Whence to say an accumulation of electric æther supports these clouds, seems an assertion built upon a very unstable foundation, whose whole superstructure may well enough be termed an air-built castle, the baseless fabric of a vision.
Add to this, that Mr. Eeles, in page 140. tells us, that himself has passed thro’ clouds resting on the sides of mountains. Ought not those clouds to have immediately discharged their electricity, and fallen? And common experience may remind us, that any cold bodies will condense vapour, whatever be their electric properties. So mirrors, or the glass of windows, in damp rooms, are most frequently found covered with dew; which, of all other bodies, ought most to be exempted from collecting vapours supported by electricity, as they are the least capable to attract or draw off that æther.
From all which, well examined, I am persuaded, gentlemen, you will be induced to conclude, that tho’ clouds may sometimes possess an accumulation of electricity, yet that this is only an accidental circumstance, and not a constant one; and thence can have no possible influence either in the elevation or support of them. I am,
GENTLEMEN, Your very humble Servant, Erasmus Darwin.
[Illustration: _Philos. Trans. Vol. L._ TAB. VI. _p. 255_.
_The grey Coot-footed_ Tringa _shot near Halifax in Yorkshire (January 1757) and Presented to me by Mʳ. Thomas Belton Florist of Worley-clough in Yorkshire. Drawn from nature of the Figures of Life by Geo. Edwards in Feb.⁴ 1757._]