Chap. I. A brief Theory of the North Magnetic Pole; and of the Mariner's Compafs-Needle, 447 Chap. VI. Of the greatest Variations that can happen at different Parallels of Latitude, 505 С НА Р. 1. The Origin, Antiquity, and Progrefs of Electricity. Opinions of various Authors on Air. A #TTEMPTS to render Electricity intelligible and plain have been to often made, and with fo little fuc cefs, that the Expectation of the Public is almost at an end; and 'till fome more effectual method be purfued than what has been hitherto practis'd, so long that wonderful Appearance of Nature will remain inexplicable. Therefore, that one fo unaccomplish'd and unlearned as I must own myfelf to be, fhou'd prefume to explain it, will doubtlefs be thought a vain and daring Effort, by MANY, who may be inclined to think that little more can be produced from my illiterate Labours, than from fop's teeming Mountain, which brought forth only a Mouse. 2. This was fo natural and obvious, that I could not help foreseeing it my felf in the ftrongest Light: The method therefore which appear'd to me the most eligible and unexceptionable, in order to guard against fuch an ill-favour'd Reflection, was, to collect the Opinions and Experiments of fome of the most celebrated and authentic Writers on this ambiguous Subject, particularly of Sir I. Newton, Mr. Haukfbee, and Dr. Franklin ; to lay their obfervations together; to compare them diligently and candidly; and to make ufe of whatever I found proper for fixed purpose of investigating the Truth. my 3. By fuch a careful, and, I think, rational method of proceeding, together with my own Experiments and Obfervations, I was encourag'd to hope that fome farther Light might be reflected on this important Subject than ever was before. 4. But in order to elucidate, and render it more inftructive and entertaining to the Reader, I must beg leave to prefix a brief account of the Origin, Antiquity, and Progrefs of it. 5. This I in fome measure anticipated by a former Publication; but as I have many Things to add to the Obfervations I then made, I now take the Liberty to place the whole here in one regular View. 6. The Term Electricity in great measure explains it felf, being deriv'd from Electron, which is the Greek Name for Amber. 7. The Ancients, fome thousand Years ago, were not unacquainted with that Property in Amber Amber of attracting light Bodies Bodies afterrubbing it; for which Reason all other Things that were afterwards found to be endu'd with the like Qualities of Attraction, &c. were call'd Electrics, and all others, Non-electrics. 8. The Reason why Electricity made fuch flow Advances in the experimental Way, for fo many hundred Years, was, from its not being known that it efcap'd thro' other Bodies into the Earth; and more particularly from not knowing that all fuch Bodies, which are now call'd Electrics per fe, were the only Bodies which could prevent fuch Escape. 9. Of Bodies which are endu'd with this Quality, Glafs is found to be one of the greatest of all, even much to exceed that of Amber itself. 10. The very first Man that we hear of, who was fo happy as to make any confiderable Improvement in Electricity, is Mr. Haukfbee, Fellow of the Royal Society, near the latter end of the laft Century; he difco-" ver'd many of the Experiments, that are now exhibited, with a glafs Tube; he alfo invented a method to turn glafs Globes and Cylinders on their Axes, and nearly of the fame Conftruction with those that are now made ufe of,fome in the common Way, others he exhaufted of their Air, and then whirl'd then on their Axes, and exhibited the appearance of Fire in various forms, and in fome, in very great plenty. B 2 II. |