I. _An Account of the Earthquake felt in_ New England, _and the
neighbouring Parts of_ America, _on the 18th of_ November 1755. _In a
Letter to_ Tho. Birch, _D.D. Secret. R.S. by Mr. Professor_ Winthrop,
_of_ Cambridge _in_ New England.
[Read Jan. 13, 1757.]
Reverend Sir,
I Beg leave to lay before you the best account I am able to give of the
great earthquake, which shook New England, and the neighbouring parts
of America, on Tuesday the 18th day of November 1755, about a quarter
after four in the morning. I deferred writing till this time, in order
to obtain the most distinct information of the several particulars
relating to it, both here and in the other places where it was felt;
and especially the extent of it.
The night, in which this earthquake happened, was perfectly calm and
serene. In the evening there was a fog over the marshes bordering on
the river Charles, which runs through this town: but this I found
intirely dissipated at the time of the earthquake, the air being then
quite clear, and the moon, which wanted but 36ʰ of the full, shining
very bright. The earthquake began with a roaring noise in the N.W.
like thunder at a distance; and this grew fiercer, as the earthquake
drew nearer; which was almost a minute in coming to this place, as
near as I can collect from one of my neighbours, who was then on the
road in this town. He tells me, that, as soon as he heard the noise,
he stopt, knowing, that it was an earthquake, and waiting for it;
and he reckoned he had stood still about 2’, when the noise seemed
to overtake him, and the earth began to tremble under him: but, as I
doubted, whether it were so long, I counted several numbers to him
as slowly as a clock beats seconds; and then he said, he believed he
could have counted half an hundred, at that rate, before the noise and
shake came up to him. By his account, as well as that of others, the
first motion of the earth was what may be called a pulse, or rather an
undulation; and resembled (to use his own comparison) that of a long
rolling, swelling sea; and the swell was so great, that he was obliged
to run and catch hold of something, to prevent being thrown down. The
tops of two trees close by him, one of which is 25, the other 30 feet
high, he thinks waved at least ten feet (and I depend on his judgment
in this particular, because he judged right of the height of the trees,
as I found by actual mensuration); and there were two of these great
wavings, succeeded by one, which was smaller. This sort of motion,
after having continued, as has been conjectured, about a minute, abated
a little; so that I, who was just then waked, and, I suppose, most
others, imagined, that the height of the shock was past. But instantly,
without a moment’s intermission, the shock came on with redoubled noise
and violence; though the species of it was altered to a tremor, or
quick horizontal vibratory motion, with sudden jerks and wrenches. The
bed, on which I lay, was now tossed from side to side; the whole house
was prodigiously agitated; the windows rattled, the beams cracked, as
if all would presently be shaken to pieces. When this had continued
about 2’, it began to abate, and gradually kept decreasing, as if it
would be soon over: however, before it had quite ceased, there was a
little revival of the trembling and noise, though no-ways comparable
to what had been before: but this presently decreased, till all, by
degrees, became still and quiet. Thus ended this great shock. It was
followed by another about an hour and a quarter after, viz. at 5ʰ 29’.
This, though comparatively small, was very generally perceived, both as
to its noise and trembling, by those who were awake. On the Saturday
evening following, viz. the 22d of November, at 27’ after eight, there
was a third, more considerable than the second, but not to be compared
with the first. And on Friday the 19th of December in the evening,
exactly at ten o’ clock, there was a fourth shock, much smaller than
either of the former, though, like them, preceded by the peculiar noise
of an earthquake. The whole lasted but a few seconds; but the jarring
was great enough to cause the window-shutters and door of the room, in
which I then was, to clatter. The sky was perfectly clear, and there
was a very gentle and scarcely-perceptible gale at S.W. These four are
the only shocks, that I have been sensible of from the 18th of November
last to this date; tho’ more are said to have been felt in other parts
of the country to the northward of us.
As to the duration of the great shock, people have differed widely,
viz. from 1’ to 6 or 7. Our printed accounts have generally fixed it
to about 2’, or 3 at the most; but as these were only the uncertain
guesses of persons, who had no rule to guess by, no dependence can
be had on them. I am well satisfied, that with us it continued 4’,
or rather 4’ 1-half; taking in the whole of the time, from the first
agitation of the earth till it was become perfectly quiet; tho’ the
violence of the shock did not last above half so long. This I am
assured of, partly from the observations of some gentlemen, who were
up, and looked on their watches, when it began and ended; one of whom
tells me it was 4’, and another, that it was near 5; and partly from
my own observations, which were as follow. The preceding noon I had
adjusted both my clock and watch to the apparent time, by a meridian
line; and the following noon I found, that the watch had kept time
exactly. Being awaked by the earthquake, I lay till the violence
of it seemed to be over for the second time, the first abatement
happening just after I waked. Till then I forbore to rise, because the
agitation was so vehement, that I concluded it would be difficult, if
not impracticable, to go from the bed to the chimney, without being
thrown down; and therefore thought it best not to attempt it. The
space of time, in which I lay awake, I cannot think to be much, if any
thing, less than 2’. This was the conjecture I formed at that time;
though, it being but conjecture, I would not lay very great stress
upon it, were it not supported by concurring observations. On the
second abatement I rose, and lighting a candle, looked on my watch,
and found it to be 15’ after four. The shock then was not quite over,
but the windows continued rattling for about a minute longer, as near
as I can remember; for the shock went off very gradually. As soon as
I had looked on the watch, I went directly to the clock, which was in
another chamber, that I might see whether that agreed with the watch,
and found that it was stopt at 4ʰ 11’ 35’'. Its stopping, however, was
not immediately owing to the violence of the shock, though several
clocks, and watches too, at Boston, are said to have been stopped by
it, but to the following accident: Having some time before used a
pretty long glass tube, in a particular experiment, I had shut it up
in the clock-case for security; and this tube, being overthrown by the
earthquake, lodged against the pendulum, and stopt its motion. By this
accident, the beginning of the earthquake, I conceive, is determined
with all the exactness, that can be desired; for, so far as I can
learn, the first shake was violent enough to overset so tall, slender
a body, and standing in a position so near a perpendicular, as that
tube; and it was impossible for the pendulum to make one oscillation,
after the tube had struck against it. But I am not able to fix the
end, nor consequently the duration, with the same exactness: however,
from the time, when the clock stopt, to my looking on the watch, it was
about 3’ 1-half; and the jarring was not quite over till about a minute
after this: so that I think I speak within bounds, if I say, that this
shock with us lasted at least 4’. In other places, its duration might
possibly be different. I was careful to note the time, when we had it,
as exactly as I could, in hopes, that, by comparing it with the like
accounts from distant places, we might be able to judge, with a good
degree of exactness, of the course of this earthquake, the place of its
origin, and the velocity of its progress. But all the accounts of the
time, which I have yet seen, are so very lax, that no just conclusions
can be drawn from them, with respect to either of these points. What
I have been able to collect with relation to them, I shall set down
presently.
Those, who suppose the duration much shorter, as 1’ 1-half, or 2’,
urge, that a minute is a longer space of time than most people are
aware of; which is very true: but it should also be considered, that
if we judge the length of any space of time by the number of ideas,
which pass through our minds in that time; a very great fright,--a
fright so great, as to take intire possession of the mind for a time,
and shut out every idea except that of the present danger, will make
us judge the time to be much shorter than it really is. And this, I
make no doubt, was the case with many; the surprise, into which they
were thrown, being such, as to keep out every idea, except that,
which happened to strike their minds with the greatest force at the
beginning. Thus, several perceived no noise distinct from that, which
was occasioned by the crackling of their houses, and the disturbance of
the moveables in them; while others, who were waked by the noise, and
ran from one room to another, have told me, that they felt nothing at
all of the shake. For this reason, the conjectures, which persons in
these circumstances made, as to the duration of the shock, ought not to
be put into the balance with the actual observations made by watches.
The course of this earthquake seems to have been nearly from N.W. to
S.E. My neighbour before-mentioned, who was then abroad, and informed
me, that the noise began about the N.W. told me at the same time, that
it passed off towards the S.E. and that he heard the noise in that
quarter gradually abating, as it became more distant, for about the
same space of time after the shock was over here, as he heard it in
the N.W. before the shock began here. Other accounts, which I have
since met with, agree with this. Those, who were in such clear open
places, could make the best judgment in this matter; for such, as were
within doors, or surrounded with buildings, might easily be misled by
the various reflections of the sound. I am induced to give the greater
credit to this information by what I observed myself: for a key, which
was thrown from off a shelf in my house, was found at a place on the
floor, which bore very near N.W. of the place, from which it fell;
though the situation of it before its fall was such, that it might have
been thrown in any direction, except towards the S.E.
An account, which we have lately received from the West-Indies,
agrees very well with the supposition, that our earthquake proceeded
south-eastward. The account is, that 'on the 18th of November, about
two o’clock in the afternoon, the sea withdrew from the harbour of
St. Martin’s, leaving the vessels dry, and fish on the banks, where
there used to be three or four fathom water; and continued out a
considerable time; so that the people retired to the high land,
fearing the consequence of its return; and when it came in, it arose
six feet higher than usual, so as to overflow the low lands. There
was no shock felt at the above time.’ As this extraordinary motion of
the sea happened about 9ʰ after our great shock, it seems very likely
to have been occasioned by the same convulsion of the earth. Now if
this earthquake went off south-eastward into the Atlantic, it must
have passed considerably to the eastward of St. Martin’s; and, in
fact, it did not reach that island, there being no shock felt there.
The motion of the sea then was owing to a great agitation raised at a
considerable distance in some part or other of the ocean, where the
earthquake passed, and from thence propagated to that island. Nor is
the length of time greater than what seems to be necessary for this
effect. The earthquake itself, at the rate it moved with us, would be
some hours in going from hence to the distance of St. Martin’s: for
sound would be about 2¼ʰ in moving to such a distance; and the progress
of the earthquake was slower than that of sound, as appears from hence,
that the roar of this earthquake arrived here near a minute before
the shake. The rest of the 9ʰ might well be spent in conveying the
motion excited in the water, from the place where it was excited, to
St. Martin’s; for the waves raised thereby could not move with near the
velocity of sound.
It is worthy of remark, that, of the five great earthquakes, which
this country has felt since its settlement by the English, two have
gone nearly in the same track as this last did. The first, which was
on June 2. 1638, 'came from the northward, and passed southward.’ By
the description given of it, it was very much like our late earthquake,
only perhaps not quite so violent. 'The noise and shakes of the
earthquake, October 29. 1727, seemed,’ it is said, 'to come from the
north-westward, and to go off south-easterly; and so the houses seemed
to reel.’ As to the great earthquakes of 1658 and 1662, we have no
account of the courses, which they went in. But, from the other three,
it may be reasonably conjectured, that the source of our earthquakes,
or the place in which they originate, is in some part of Canada, or
perhaps beyond it.
The extent of this earthquake seems to have been greater than that of
any of our former earthquakes. This province of the Massachusetts-bay,
or rather the province of New Hampshire, about the latitude of 43°
north on the sea-coast, seems to have been the center of it, or the
place of its greatest violence, and the shake to have been less
considerable each way from hence towards the S. W. and N. E. By the
accounts we have from the S. W. the shock was less at New York than it
was with us; and still less at Philadelphia, which is farther towards
the S. W. By the best information I can procure, the limit toward the
S. W. was Chesopeak-bay in Maryland, the shock having been felt on
the eastern side of that bay, and not on the western. For the other
limit toward the N. E. we are informed, that the earthquake was felt
at Annapolis Royal in Nova Scotia, though in a much less degree than
with us. It shook off a few bricks from the tops of some chimnies, but
was not perceived by vessels on the water. And a letter from Halifax
says, 'The earthquake, which happened in the W. extended itself to this
place, tho’ scarcely perceivable here.’ But it was not at all felt by
our army, which lay encamped at Seganecto, about 100 miles N. from
Halifax. Thus Halifax seems to have been very near the N. E. limit.
I am not able to ascertain its eastern and western limits; but it
extended to all our back inland settlements; and was perceived, though
in a very small degree, by our army at Lake George, distant from hence
about 130 miles N. W. by W. But it was not felt at all at the British
fort of Oswego, situate on the south-eastern shore of Lake Ontario,
and distant from hence about 230 miles W. by N. So great was the shock
in the Atlantic, 70 leagues to the E. of Cape Anne, that the people on
board a vessel there were suddenly surprised, just at the time of our
earthquake, supposing they had run a-ground; till, on throwing over the
lead, they found they had more than 50 fathom water. The extent of the
earthquake E. and W. from Halifax to Lake George was about 550 miles;
and its extent along the sea-coast, from N.E. to S.W. at least 800
miles. But if the agitation of the water at St. Martin’s was occasioned
by our earthquake continued into the Atlantic, as was conjectured
above, its extent, in a direction toward the S. S. E. must have been at
last 1900 miles.
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.