Experiments and Observations Tending to Illustrate the Nature and Properties of Electricity

I may perhaps be thought too minute in some of the before-mentioned Particulars; but in Inquiries abstruse as these are, where we have so little a priori to direct us, the greatest Attention must be had to every Circumstance, if we are truly desirous of investigating the Laws of this surprizing Power. For, as has been said upon another Occasion by my ever honoured Friend Martin Folkes, Esq; our most worthy President, "that Electricity seems to furnish an inexhaustible Fund for Inquiry; and sure Phænomena so various and so wonderful can arise only from Causes very general and extensive, and such as must have been designed by the Almighty Author of Nature for the Production of very great Effects, and such as are of great Moment to the System of the Universe."

If these Observations receive the Countenance of this learned Society, I shall think myself sufficiently recompensed, and am,

Gentlemen, with the highest Esteem,your most Obedienthumble Servant,W. Watson.FINIS

1

Dr. Gowin Knight, F. R. S.

2

I call Electrics per se or originally-electrics, those Bodies, in which an attractive Power towards light Substances is easily excited by Friction; such as Glass, Amber, Sulphur, Sealing-wax, and most dry Parts of Animals, as Silk, Hair, and such like. I call Non-electrics or Conductors of Electricity, those Bodies, in which the above Property is not at all or very slightly perceptible; such as Wood, Animals living or dead, Metals and vegetable Substances. See Gray, Du Fay, Desaguliers, Wheler, in the Philosophical Transactions.

3

I have constantly observed, that the electrical Attraction through Glass is much more powerful, when the Glass is made warm, than when cold. This Effect may proceed from a two-fold Cause: First, warm Glass does not condense the Water from the Air, which makes the Glass, as has been before demonstrated, a Conductor of Electricity: secondly; As heat enlarges the Dimensions of all known Bodies, and consequently causes their constituent Parts to recede from each other, the electrical Effluvia, passing in straight Lines, find probably a more ready Passage through their Pores.