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Boston. Published by lilhard. Gray & Co

A and C, taken above or below the double horizontal line, and of those drawn from centres, B and D, taken to the right or left of the vertical line, do, with half the central number, make just 180.

It may be observed, that there is not one of the numbers but what belongs at least to two of the different circular spaces; some to three, some to four, some to five; and yet they are all so placed as never to break the required number 360, in any of the twenty-eight circular spaces within the primitive circle.

These interwoven circles make so perplexed an appearance, that it is not easy for the eye to trace every circle of numbers one would examine, through all the maze of circles intersected by it; but, if you fix one foot of the compasses in either of the centres, and extend the other to any number in the circle you would examine belonging to that centre, the moving foot will point the others out, by passing round over all the numbers of that circle successively. I am, &c.

B. FRANKLIN.

TO JARED ELIOT.

Northeast Storms begin at the South. Account of a Copper Mine.- Subscriptions for an Academy in Philadelphia.

DEAR SIR,

Philadelphia, 13 February, 1749-50.

You desire to know my thoughts about the northeast storms beginning to leeward. Some years since, there was an eclipse of the moon at nine o'clock in the evening, which I intended to observe; but before night a storm blew up at northeast, and continued violent all

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night and all next day; the sky thick-clouded, dark, and rainy, so that neither moon nor stars could be seen. The storm did a greal deal of damage all along the coast, for we had accounts of it in the newspapers from Boston, Newport, New York, Maryland, and Virginia; but what surprised me was, to find in the Boston newspapers an account of an observation of that eclipse made there; for I thought, as the storm came from the northeast, it must have begun sooner at Boston than with us, and consequently have prevented such observation. I wrote to my brother about it, and he informed me, that the eclipse was over there an hour before the storm began. Since which I have made inquiries from time to time of travellers, and of my correspondents northeastward and southwestward, and observed the accounts in the newspapers from New England, New York, Maryland, Virginia, and South Carolina; and I find it to be a constant fact, that northeast storms begin to leeward; and are often more violent there than farther to windward. Thus the last October storm, which with you was on the 8th, begun on the 7th in Virginia and North Carolina, and was most violent there.*

As to the reason of this, I can only give you my conjectures. Suppose a great tract of country, land and sea, to wit, Florida and the Bay of Mexico, to have clear weather for several days, and to be heated by the sun, and its air thereby exceedingly rarefied. Suppose the country northeastward, as Pennsylvania, New Eng

* Professor Bache, of the University of Pennsylvania, has shown, that the eclipse of the moon, here alluded to, happened in the evening of the 21st of October, 1743; as may be seen in his tract entitled, “An Attempt to fix the Date of the Observation of Dr. Franklin, in Relation to the Northeast Storms of the Atlantic Coast of the United States," published in the Journal of the Franklin Institute, in the year 1833. It appears that Dr. Franklin was the first discoverer of the above facts respecting northeast storms. — Editor.

land, Nova Scotia, and Newfoundland, to be at the same time covered with clouds, and its air chilled and condensed. The rarefied air being lighter must rise, and the denser air next to it will press into its place; that will be followed by the next denser air, that by the next, and so on. Thus, when I have a fire in my chimney, there is a current of air constantly flowing from the door to the chimney; but the beginning of the motion was at the chimney, where the air being rarefied by the fire rising, its place was supplied by the cooler air that was next to it, and the place of that by the next, and so on to the door. So the water in a long sluice or mill-race, being stopped by a gate, is at rest like the air in a calm; but as soon as you open the gate at one end to let it out, the water next the gate begins first to move, that which is next to it follows; and so, though the water proceeds forward to the gate, the motion which began there runs backwards, if one may so speak, to the upper end of the race, where the water is last in motion. We have on this continent a long ridge of mountains running from northeast to southwest; and the coast runs the same course. These may, perhaps, contribute towards the direction of the winds, or at least influence them in some degree. If these conjectures do not satisfy you, I wish to have yours on the subject.

I doubt not but those mountains, which you mention, contain valuable mines, which time will discover. I know of but one valuable copper mine in this country, which is that of Schuyler's in the Jerseys. This yields good copper, and has turned out vast wealth to the owners. I was at it last fall, but they were not then at work. The water is grown too hard for them, and they waited for a fire-engine from England to drain their pits. I suppose they will have that at work next summer; it costs them one thousand pounds sterling.

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