De Luc's Account of the mines in the Hartz foreft in Germany, alfo Bergman's Physical Geography; and Muffchenbrock's Introductio ad Phil. Natur. artic. 2299. E.]

[N. B. Since writing the above, M. Mairan's Traité Phyfique et Hiftorique de l'Aurore Boreale, zade edit. has fallen into my hands. The theory is fingular perhaps, but the hiftorical collection is elaborate and important. It poffibly was to fuperfede the neceffity of this theory, that Dr. Franklin has fuggefted a caufe for the frequent appearance of the auroras at the approach of winter: and I find by Mairan's table, that out of 1441 auroras which are recorded during 1168 years, 212 were feen in the months of October, and 202 in thofe of March; which gives the preference to October, contrary to Muffchenbroek, and conformable to Dr. Franklin.-Mairan also makes it clear that the auroras were formerly very unfrequent; infomuch that the number which appeared from 1722 to 1751 inclufively, (amounting to 989 in only 30 years) more than doubles according to his table thofe that had appeared during the space of 1138. years before. He seems also to have proved that the auroras are neither perpetual, ancient, nor unufually brilliant towards the high latitudes in this northern hemifphere; and that they are perhaps never seen in it at fo low latitudes as 36°.-In the Southern hemifphere, he confirms their appearance from Ulloa; who fent him a very fatisfactory account by letter, of fome that he had feen in doubling the land at Cape Horne; and Frezier alfo appears to have feen the like in the fame fituation.-Refpecting the height of the auroras, he exhibits a computation made by various philofophers in various manners of certain particular ones, and ftates the average of them at 175 leagues high (of which leagues 25 go to a degree); the lowest being 47 leagues, and the higheft 275 leagues: And in another place he computes the average of them at 200 leagues high, which is 8 degrees or 556 English miles.- See Mairan, p. 554; 547-554; 82-93; 379-389; 104, 437; 438-441; 56-7, 405-6, 412, 433-6: alfo Newton's Optics, Qu. 28.

To conclude; when I first read the above paper in May laft, I thought I faw true principles contained in it, though I felt difficulties in their application. Upon a due confideration however of the locality of the auroras, the irregular periods of their appearance, and the fmall elevation of the atmosphere; I find thefe difficulties to be infuperable. I have therefore applied the fame principles of "electri"cally charged air, and a non-conducting earth," to another hypothefis; which feems to admit a nearer approximation to the truth. For various reafons however, I make no alterations in the notes; which tend to establish two fingular facts; viz. that the air is moist and warm at unexpected heights above, and that the earth is frozen at unexpected depths below. July 1779. N.B. Vide Addenda. E.]

The

The body

Of

BENJAMIN FRANKLIN, Printer,
(Like the cover of an old book,
Its contents torn out,

And stript of its lettering and gilding)
Lies here, food for worms;

Yet the work itself shall not be loft,
For it will (as he believed) appear once more,
In a new

And more beautiful edition,
Corrected and amended
By

The Author *.

[A news-paper, in which I have feen this copy of Dr. Franklin's epitaph on himself, fays that it first appeared in a Bofton news-paper eftablished and printed by Dr. Franklin. E.]

1

APPENDIX;

Containing additional Papers proper for infertion in the foregoing work.

[G. P.]

Rules for a Club formerly established in
Philadelphia.

Previous question, to be answered at every meeting. HAVE you read over these queries this morning, in order to confider what you might have to offer the Junto [touching] any one of them? viz.

1. Have you met with any thing in the author you laft read, remarkable, or fuitable to be communicated to the Junto? particularly in hiftory, ⚫ morality, poetry, phyfic, travels, mechanic arts, or other parts of knowledge.

[This was an early performance; and carries along with it an air of fingularity, accompanied with fuch operative good fenfeand philanthropy, as characterizes it for Dr. Franklin's. It did not come into my poffeffion early enough for infertion in the body of the work; but it belongs to the divifion of General Politics after p. 81. as the chief ends propofed by it tend to the advancement of a State.. -The club for which it was written, was held (as I have supposed) in Philadelphia; and if I am well informed was compofed of men confiderable for their influence and difcretion; for though the chief measures of Penfylvania ufually received their firft formation in this club, it exifted for 30 years without the nature of its inflitution. being publicly known. E.]

с 2. What

2. What new ftory have you lately heard agreeable for telling in conversation ?

3. Hath any citizen in your knowledge failed • in his business lately, and what have you heard of the cause ?

4. Have you lately heard of any citizen's thriving well, and by what means?

5. Have you lately heard how any present rich man, here or elsewhere, got his eftate?

6. Do you know of any fellow citizen, who has lately done a worthy action, deferving praise and imitation? or who has committed an error proper for us to be warned against and avoid?

[7. What unhappy effects of intemperance have you lately obferved or heard? of impru<dence? of paffion? or of any other vice or folly? 8. What happy effects of temperance? of prudence? of moderation? or of any other • virtue ?]

· 9. Have you or any of your acquaintance ⚫ been lately fick or wounded? If so, what reme• dies were used, and what were their effects?

10. Who do you know that are shortly going voyages or journies, if one fhould have occafion < to fend by them?

11. Do you think of any thing at present, in ⚫ which the Junto may be ferviceable to mankind? to their country, to their friends, or to them• felves?

12. Hath