the top of the highest Hall or Stair-cafe, or to any point of elevation whatever. Can it then be reasonably doubted, whether the flash of real Lightning that was obferv'd to break forth to the iron Rod at the top of Profeffor Richmann's House, was at the very inftant he was ftruck Dead with the Ball of Lightning at the bottom?

325. This Cataftrophe, it is prefum'd, * would not have happen'd, had the Chain, or t any other part of that Apparatus from the Houfe-top, touch'd the Building, as the Elec *tricity would have been readily communicated. thereby to the Earth." See Gentleman's Ma gazine for July 1755. p. 312.

The CONCLUSION of PART I.

SECTION 326.,

ROM the foregoing Reasoning it is Fevident that I have fhewn no partial regard to my own Experiments more than to those of others, as I was well fatisfied they came from approv'd Authors, or elfe were fuch Experiments as are well known; my defign in exhibiting them being to evince, by plain demonftration, the actual Existence of fuch a First Principle, which though it has been too long either doubted or denied, yet must be admitted and allow'd, before PhilofoY

phy

phy can ever flow naturally and smoothly on, as if in its true and proper Channel, and before we can proceed to deduce any Thing a priori*. These Confiderations convinc'd me of the abfolute neceflity of a fufficient number of experimental Proofs of the Exiftence and wonderful Properties of this Principle, and for these Reasons and fome other I found myself under a kind of neceffity of reconfidering fome Experiments which I had given the World in my former Publications, in order,

327. Firft. To correct Errors, which, I have fince found, I had then fallen into.

328. Secondly. Altho' in my former Effays on Electricity I always kept my Eye fix'd on that which plainly appear'd to be the most principal Object, viz. that the electrical fubtile Fluid was the very identical Æther or univerfal ætherial Medium fo much infifted on by Sir Ifaac Newton and the learned Bishop Berkeley; and though I had more than once taken notice of that portentous Paragraph with which Sir Ifaac concludes his Principia, and of his judicious Reasoning thereon, whereby to account for the feeming active properties of inert matter, which appearances, he informs us, are the effects of the Force and Action of the fubtile Fluid contain'd in its pores: Altho', I fay, I

See Princip. Lib. 3. Prop. 13. Where Sir Isaac shews us how far we must proceed analytically, i. e. a pofteriori; and when we may fafely proceed fynchetically or a priori.

had

had taken fome notice of these things before, yet I had not pursued the subject to far as to prove the existence of that Fluid in the pores of grofs Bodies by fuch convincing Experiments" as are produced from Section 75 to Section 105, though almost every other Experiment in Electricity when examin'd will be found to confirm in fome degree or other the fame thing. This is fo obvious, that none, who confiders those Experiments, can have the leaft doubt of the truth of what I have advanc'd; and every true Philofopher, i..e. every unprejudiced lover of Science, that has any regard either for the honour or memory of the illuftrious Sir Ifaac Newton, will examine with due attention, the various Experiments, whereby the feveral operations of natural Caufes and Effects may fucceffully be traced and accounted for.

329. Thirdly. Another Reason which induced me to engage in this Subject was to settle that important Queftion how a Fluid fo furprisingly elastic as the electrical Medium is found to be, can be retain'd within certain Limits in the open Air*, where, to appearance, there is nothing to prevent it from inftantly escaping to regain an Equilibrium.

330. Fourthly. My chief Reason was to pave the way to the principal Thing I had in view, and which I have made the Subject of the second Part of this Work, viz. A ftrict Enquiry

* When accumulated on the prime Conductor, &c.

Y 2

into

Into the Nature and Properties of that abftruse Phænomenon FIRE; Being fully convinced that by means of the beams of Light reflected on it from electrical Experiments, that ambiguous and difficult Subject might be render'd much more clear and intelligible than it was ever capable of being made before.

331. Amongst my former Errors which (as hinted above) I intended to correct, the following was the greatest: In my first Effay and fome part of my fecond (publifh'd a few Years fince) I, like every other Writer on Elec tricity, being much attached to the Term Attraction, made use of it on almost every occafion, without ever confidering how unlikely it was that what was fo exceedingly elaftic and impelling, fhould at the fame time attract, Attraction and Impulse being as deftructive of each other as Light and Darkness; and a thing may as well be cold and hot, white and black, as at the fame time attract and repel. So that I should have had nothing to keep me in countenance, had I not found the mistake fo general, as that fcarce any one Writer on the subject efcap'd it.

332, I have before obferv'd that Sir Ifaac Newton when speaking of an æthereal Medium, describes it to be much like Air in all Refpects, but far more fubtile. In this light I have purfued my enquiries into the nature and properties of the fubtile Medium fo far as it is difcoverable by the electrical Apparatus, and have always found it ftrictly to agree with Sir Ifaac's definition

...

nition, and can therefore affirm that whoever examines the electrical Medium on the fame Plan will not lose his labour, but will find the electrical Fluid, to be a moft intelligible Thing*. For if truth may be collected from the greatest number of the clearest Experiments, and the moft indubitable Facts, he who confiders the Electricity, as it is called, as an univerfal pure Air, must be convinced of the truth of what I have afferted.

333. But as this univerfal Principle proves to be real Fire, it may perhaps be expected that I should enter on a particular explication of its Offspring Light, the true Effence of which we know but very little of, nor has the difcovery of an univerfal Fire in Nature been as yet fufficiently cultivated to afford us proper requifites for our farther enquiries on Light with fuccefs; or indeed at all to enlarge our Ideas of it. What however feems rational to conceive of it is, that fo univerfal an Effect must derive its origin from as univerfal a Cause. Mr. Chambers and others, who have carefully collected the opinions of the beft Authors extant in their time are fomewhat obfcure in their de

finitions of it. - Light according to Mr. Chambers is that Senfation occafion'd in the Mind by the view of luminous Bodies; or that property in Bodies, whereby they are fitted to excite thofe Senfations in us.' Other Expofitors to the fame

Effect.

* And on any other Plan the most inexplicable. The