I shall now proceed to mention the principal effects of this earthquake, for which I can find sufficient vouchers; for many strange things have been related, which, upon examination, appear to be without foundation. Besides the throwing down of glass, pewter, and other moveables in the houses, many chimnies were levelled with the roofs of the houses, and many more shattered, and thrown down in part. Some were broken off several feet below the top, and, by the suddenness and violence of the jerks, canted horizontally an inch or two over, so as to stand very dangerously. Some others were twisted, or turned round in part. The roofs of some houses were quite broken in by the fall of chimnies; and the gable ends of some brick buildings thrown down, and many more cracked. Throughout the whole country, the stone fences were more or less thrown down. The vane upon the public market-house in Boston was thrown down; the wooden spindle, which supported it, about five inches in diameter, and which had stood the most violent gusts of wind, being snapt off. A new vane, upon one of the churches in Boston, was bent at its spindle two or three points of the compass; and another at Springfield, distant about 80 miles westerly from Boston, was bent to a right angle. A distillers cistern, made of plank, almost new, and very strong put together, was burst to pieces by the agitation of the liquor in it; which was thrown out with such force, as to break down one whole side of the shed, that defended the cistern from the weather; as also to stave off a board or two from a fence at the distance of eight or ten feet from it. In some parts of the country, particularly at Pembroke and Scituate, about 25 miles S.E. from hence, there were several chasms or openings made in the earth, from some of which water has issued, and many cart-loads of a fine whitish sort of sand. These are the principal effects of this earthquake on the land, some of which argue a very quick and violent motion of the earth. Tho' the degree of violence was doubtless different in different places, yet, that I might make some estimate of it with us, I measured the greatest distance on the ground, to which any of the bricks, which were thrown off from the tops of my chimnies, had reached, and found it to be 30 feet, and the height from which they fell was 32 feet. Now since bodies fall thro' 16 feet nearly in 1" of time; and the times, in which they fall through other heights, are in the subduplicate ratio of those heights; it follows, that the velocity, wherewith those bricks were thrown off, was that of above 21 feet in 1" of time: for the subduplicate ratio of 32 to 16 is the same as the simple ratio of 30 to a little more than 21. But the velocity was less at less heights: for the key before spoken of, as thrown from off a shelf in a chamber in my house, was not thrown so far, in proportion to the height thro' which it fell, as the bricks were from the top of the chimnies; and in my lower rooms nothing was thrown down, but a small bell in the garret was made to ring by it. Hence it appears, that our buildings were rocked with a kind of angular motion, like that of a cradle; the upper parts of them moving swifter, or thro' greater spaces in the same time, than the lower; the natural consequence of an undulatory motion of the earth.
But the agitation occasioned by this earthquake was not confined to the land: it was very sensible on the water, and even at considerable distances in the ocean. The vessels in our harbours were so shaken, that it seemed to those, who were in them, as if they were beating on the bottom. Some, that were in the bay, coming in from sea, thought they had run upon rocks or sands. One very uncommon effect of this concussion is related by several of our seafaring men, that almost immediately after the earthquake, large numbers of fish of different sorts, both great and small, came up to the surface of the water, some dead, and others dying.
The center of our former earthquakes, as well as of this, seems to have been near the river Merrimac, about the latitude of 43° north, and 40 miles north from hence; many shocks having been felt in that neighbourhood, which did not extend to this place. The late Rev. Mr. Plant of Newbury, which is situated at the mouth of that river, has given a very particular journal, in Philos. Transact. Nº. 462. of the shocks felt there from 1727 to 1741, few of which were perceived here or at Boston. I remember none after the memorable 29th October 1727, beside that on 30th January 1728, about two in the afternoon; and that on 5th September 1732, which, by his account, did considerable damage at Montreal in Canada, but it was very small at Boston. That also on 6th February 1737, about a quarter past four in the afternoon, which he calls a considerable shock, was perceived at Boston; and so was that on 7th December following, a little before 11 in the night. From the conclusion of Mr. Plant's journal, till the earthquake which is the subject of this letter, I know of none, but that which happened on Sunday June 3, 1744, at a quarter after ten in the morning. The roar of this was as loud as any I ever heard, but the shake not so great. The day was very fair and hot, with a little wind in the morning at W.S.W. which in the afternoon came round to N.N.W. The season preceding was hot and dry, there having been no rain from 23d May. On the 1st June, at four in the afternoon, Hauksbee's thermometer stood at 5,2; on the 2d, at five in the afternoon, it was at 1, with high wind at S.W.; on the 3d, at eight in the morning, it was at 19,8; and at six 1-half in the afternoon at 3,8. From the 1st June to the 2d, at the hours just mentioned, the barometer had fallen from 29,92 to 29,82; from which time it continued rising till the 4th at eight in the morning, when it was got up to 30,12; being, at the time of the earthquake, at 29,94. The rest of the month the weather was in general very hot, with many thunder-showers.
As the late Hon. Judge Dudley, who has given a very just account of the great earthquake of 29 Oct. 1727, in Philos. Trans. Nº. 437, has inserted an account of the weather in the preceding part of that year; and as our last earthquake happened at the same time of the year as that did, within 8 or 9 days (regard being had to the difference between the Julian and Gregorian styles); I hope it will not be disagreeable, if I give an account of our weather the last year: in doing which, I shall follow, as near as may be, Mr. Dudley's method, setting down the particulars in corresponding columns, that so a comparison may more easily be made between these two years.
Weather in
| 1727, O. St. | 1755, N. St. |
|---|---|
| January and February very moderate. | January, but especially February, very moderate. |
| Beginning of March, a great deal of snow, and some cold weather: afterwards, pleasant, rain at times, and once thunder and lightning. | 4th of March the greatest storm of snow we had all winter. The whole month colder than February. |
| April, for the most part, fair, pleasant. Plentiful rain, beginning and end of the month. | April, nothing very remarkable. No hot weather. Each of these four months afforded more snow and rain, than the common quantity, taken at a medium for 7 years together. |
| May, beginning, pleasant; then a great deal of rain; afterwards, cold and very dry. | First 20 days of May, dry; 14 to 18 inclusive, uncommonly hot; latter part, frequent thunder-showers. The whole month drier than the medium. |
| June, abundance of thunder and lightning. | June, ten thunder showers; 15 to 20 inclusive, uncommonly cool. The driest June since 1749. |
| July, very dry; a great deal of thunder and lightning. | July, seven thunder-showers, and a little more rain than the medium. |
| August, exceeding hot and dry. One plentiful rain. | August, not very hot; much drier than the medium. |
| September, till the middle, very hot. More hot weather than in any summer. Middle, a violent north-east storm, with a great deal of rain. | September, variable; 10 to 14 inclusive, uncommonly hot; several other days uncommonly cool. Upon the whole, the summer rather cool than hot. The hottest weather was in the middle of May. No great rains; but rather more than the medium. |
| October, a pretty deal of cold weather. 23, a great deal of rain, with the S. wind. 25, at night a hard frost. 26, Winterish weather, and a little snow. 28, Cold. Wind N.W. 29, Cold. Little wind at N.W. Evening quite calm, and a clear sky. | October, a great deal of cold weather. Thunder-showers on the 13th and 17th. Snow on the 20th, 25th, 29th, & 30th. But the quantity of rain and snow in the whole month less than the medium. |
November began with cold and wet, there falling, in the eleven first days 3,404 inches of rain; and on the 11th in the morning there was thunder and lightning with the rain; and at a quarter past two in the afternoon, the barometer was at 29,46; which was lower than it had been since the 15th of October. From thence, till the day of the earthquake, my diary stands thus:
November 1755.
| D. H. | Barom. | Hauksb. Therm. | Wind. | Weather. | Rain, &c. |
|---|---|---|---|---|---|
| 12 7¾ M | 29,78 | 63,7 | W 1 | Very fair. Somewhat foggy. | ,003 |
| 2¾ E | 82 | 51,7 | W 1 | Fair. | |
| 13 9 M | 30,14 | 68 | NW 2 | Very fair. | |
| 6¼ E | 21 | 56,8 | NNW 1 | Clear. | |
| 14 8½ M | 42 | 69,4 | 0 | Fair. | |
| 1½ E | 45 | 59 | NE 2 | Very cloudy. | |
| 8¾ E | 5 | .. | NE 1 | Clear. | |
| 15 8½ M | 4 | 74,6 | 0 | Cloudy. Hazy. White frost. | |
| 4 E | 32 | 60,5 | E 1 | Very fair. | |
| 16 0¼ M | 27 | 70,8 | 0 | Foggy. | |
| 2 E | 28 | 59,9 | N 1 | Fair. | ,013 |
| 9¼ E | 32 | .. | N 1 | Fair with clouds. Foggy. | |
| 17 8 M | 3 | 70,1 | N 1 | Cover'd. Foggy. | |
| 1½ E | 27 | 59 | E 1 | Very fair. Evenᵍ somewhᵗ foggy. | ,001 |
| 18 4¼ M | 17 | 74,1 | 0 | Clear. A violent earthquake. | |
| 8 M | 16 | 78 | 0 | Very fair. Great white frost. | |
| 3¼ E | 11 | 58,3 | E 1 | Very fair and hazy. | ,017 |
| 10 E | 08 | 69,1 | 0 | Clear. Somewhat hazy. |
From this time the barometer rose till the 20th, when, at 8¼ M. it was up at 30,44, the sky covered, wind N 2. Then it fell till the 23d at 6½ E, when it was so low as 28,87; which was lower than it had been since the 6th of February last. The afternoon of the 22d, and night following, when we had another shock, it was calm, and rained 1,205 inches. This leads me to observe, that though the serenity, as well as calmness, of the air, is a circumstance taken notice of in many earthquakes, both in this and in other parts of the world; yet it does not always obtain, at least in the smaller shocks, and, so far as I have had opportunity to observe, the calmness of the air has more constantly attended upon earthquakes, than its clearness. The white frost on the morning of the earthquake, which, when melted, I found to be of the depth of 17/1000 of an inch, was almost double of any white frost we have had for seven years past, and about five or six times as great as we commonly have. The barometer and thermometer underwent no alteration at the time of the earthquake: only, my barometer, which has an open cistern of quicksilver, and stood in a chamber, was so agitated, that part of the quicksilver was dashed over the sides of the cistern, and scattered upon the floor. This cistern was a cylindric cup, whose sides were an inch higher than the surface of the quicksilver.