This plate is copied exactly from a Supplement issued with the Pilot
Chart for October, 1889 (published Sept. 27th), with only the addition
of the tracks of the two storms (as indicated by later data) and the
tracks of a few vessels (see small charts dated Sept. 3, 4-7, 10).
Considering the early date of publication, the wide expanse of ocean
covered by the charts, and their essential accuracy (as indicated by
later data), it must be acknowledged, I think, by anyone who is at all
acquainted with the difficulties incident to this sort of work, that
this supplement to the Pilot Chart hit more closely to the truth in
this matter than would probably be possible under similar circumstances
in one case out of ten. Had later data materially modified conclusions
drawn at such an early date, it could not have been a matter of
surprise, although this prompt publication would still have served a
most valuable purpose in interesting navigators to contribute data
likely to help us in establishing the facts. Indeed, the following
quotations from the Pilot Chart and Supplement illustrate exactly what
was desired, and what was actually accomplished by this publication:
"This preliminary publication, issued two weeks after the storm reached
our coast, well illustrates the cordial support this office receives
from masters of vessels in its efforts to collect and utilize data
regarding marine meteorology. It is desired to collect as complete data
as possible regarding this storm, in order to publish a final report,
and the present publication will be useful as a good working basis for
a more complete detailed study of the hurricane." Also, "Special
attention is called to the fact that this preliminary publication is
only intended to give a brief outline of the facts as indicated by data
received up to date of publication." Moreover, the name, nationality,
and rig of every vessel whose report had been received in time to be
used was published, and every statement made in the accompanying text
was based on an exhaustive study of all the data.
It is interesting to note how slightly the very complete data now at
hand have modified this hastily-prepared history, and all the
circumstances urge similar quick work and prompt publication in every
case, before other storms and other conditions have dulled public
interest and directed attention elsewhere. The track of the easternmost
of the two storms, as plotted on the first little chart, shows that it
moved more rapidly than was anticipated, and recurved farther north:
the fact is, its very existence was not even suspected till _two hours_
before the final draft of the maps was made, and then only because the
German steamship "Savona," from Baltimore for Brazil, suffered such
damage from the hurricane on Sept. 5th (see chart dated Sept. 3rd for
position) that she was obliged to run in to St. Thomas for repairs, and
our consul, Mr. M. A. Turner, forwarded her report by the first steamer
to New York. The following is a brief extract from this report,
beginning at 10 P.M., Sept. 4th: "Full hurricane, ship lying in trough
of sea, laboring heavily and shipping much water. Cargo shifted;
jettisoned 600 barrels of flour and 60 tons of coal. Broke steam
steering gear and wheel, found rudder adrift, 3 feet of water in the
hold, foundations of engines seriously loose and getting worse. Bore up
for St. Thomas."
It is impossible, in the space at my disposal, to refer even briefly to
the reports of the few vessels whose tracks are plotted on the charts:
the stanch steamship "Earnmoor," foundering in the heart of the
hurricane on Sept. 5th, eleven of her crew of thirty escaping in an
open boat, and of these only seven surviving that fearful drift of
twenty-three days; the "Sépet," between the two storms and escaping
both; the "Lassell," from the tropics to Block Island, all the way in
the grasp of the hurricane, without a sight of sun, moon, or stars, to
fix her position; the "Ada Bailey," rolling in the long swell off
Hatteras and watching the early indications of the approaching storm
for nearly a week before it struck her; the "Hernan Cortes," forced to
stand off into fearful danger by the still greater danger of a
lee-shore at Hatteras; and the "City of New York," "Teutonic," and
"City of Rome," starting on their Titanic race from Liverpool for New
York the day after this great hurricane swept past St. Thomas, and
reaching their goal with it, and in spite of all its fury. I must
dismiss this whole interesting history with the following abstract of
the report of Capt. Simmons, of the British brigantine "Victoria,"
whose original report is brief and to the point, like all the rest (see
track of the "Victoria," northwest from St. Thomas, on the first small
chart):
I passed through the cyclone, resulting in the total loss of the spars,
sails, etc., of my vessel. The SE. sea became so heavy that I was
obliged to heave-to. The sky was one sheet of dark gray, at times
approaching black. The lightning was excessive only during the latter
part of the storm; it appeared as a continuous quivering sheet around a
great part of the horizon, extending about 10° above it and lasting
many seconds, unaccompanied by thunder; the compass could not be read,
the card spinning so that the points were indistinguishable. The lowest
barometer reading was 27.86 (aneroid, corrected by comparison at Boston
shortly before and at Halifax the following month).
{PLATE: THE ST. THOMAS-HATTERAS HURRICANE OF SEPTEMBER 3-12, 1889.
[Illustration: _Sept. 3_.--A hurricane of great intensity is passing
close to the northward of St. Thomas, moving about W. NW. Lowest
barometer at St. Thomas during the day, 28.97. Steepest observed
barometric gradient (between St. Thomas and Puerto Rico), .75 inch in
65 miles. The cyclone is a large one, and of terrific energy,--an
enormous whirlwind more than 500 miles in diameter, with a central calm
area about 16 miles in diameter. It was experienced with destructive
violence amongst the Windward Islands, from Martinique to Barbuda, on
the 2d, and the vortex passed over St. Christopher's about midnight,
the central calm lasting from 10.15 p.m. of the 2d till 12.45 a.m. of
the 3d. There are evidences of another hurricane about 1,000 miles
eastward of the first, moving about W. NW.]
[Illustration: _Sept. 4_.--The hurricane is central north of Puerto
Rico, where strong northerly, westerly, and southerly gales are
experienced, but not of full hurricane force. During the forenoon its
massive, towering cloud-bank is clearly visible from Turk's island, 300
miles away, causing great alarm till it is seen to be moving well to
the northward of the island. A violent storm in Santo Domingo this
afternoon seems to be either an offshoot from the cyclone or the effect
of another storm crossing the island to join the great
hurricane--possibly a storm that was felt at Curaçao the previous day.
The second hurricane has continued its motion toward W. NW. and its
present position is clearly indicated about the eastern limits of the
Chart.]
[Illustration: _Sept. 5_.--The hurricane is moving rather slowly along
a northwesterly course, toward Hatteras. The enormous seas started by
the great whirlwind during its progress thus far have overspread almost
the entire western half of the Atlantic: heavy northeasterly swell at
Jamaica and through the Windward Channel; northeasterly and easterly,
all along the Bahama Islands and northern Florida; very heavy surf at
Bermuda; long rolling swell from S. SE. off Hatteras, perceptible as
early as the 2d and increasing daily; long, low southerly swell off
Nantucket as early as the 4th, when the storm-center was 1,300 miles
away. The second hurricane is moving northwestward, and is beginning to
recurve about 600 miles S. E. from Bermuda.]
[Illustration: _Sept. 6_.--The concentric isobars on the Chart show
that the hurricane is now central about midway between Bermuda and
Eastern Cuba, with barometric pressure at the center probably below
28.40. All the characteristics of a tropical cyclone are still
exhibited, and to a marked degree: storm area noticeably circular in
outline; very steep gradients and enormous wind velocities near the
center; sudden shifts of the wind in terrific squalls; heavy driving
rain mingled with foam caught up from the crests of the waves; sky of
inky blackness, with masses of flying scud so low as to touch the
masts. Close by, in front, and on either side, calm, sultry, hazy
weather, with a tremendous swell rolling in from the direction of the
distant but massive cloud-bank of the hurricane. A long ridge of high
pressure is building up to the northward of the hurricanes.]
[Illustration: _Sept. 7_.--The hurricane continues its slow but steady
march toward Hatteras. Yesterday morning the observer at Santiago de
Cuba reported the cyclone recurving. This morning the meteorologist at
Havana, 900 miles away, reports the cyclone's movements, guided by the
motions of the upper clouds,--the cirrus veil that overspreads the
entire sky with a thick haze, and the long feathery plumes of cirrus
cloud that are faintly visible above it, radiating from the distant
storm. The influence of the great hurricane begins to be felt along the
outer edge of the Gulf Stream, below Hatteras. A heavy surf is rolling
in on the coast all the way from Cape Florida to Block Island, and the
long southerly swell has reached beyond Sable Island to Cape Breton.
The second hurricane is moving NEd., and a ridge of high pressure is
extending Sd. between the two.]
[Illustration: _Sept. 8_.--The hurricane is central about the axis of
the Gulf Stream, off Hatteras. The area of high barometer in advance is
retarding its northward progress, and preventing it from recurving to
the northeastward. The heavy surf and the increased height of the
tides, due to the storm-wave of the hurricane, begin to attract general
attention and to cause damage along the low-lying portions of the coast
between Norfolk and Newport; warm, moist ocean air is being driven in
over the cold inshore current, and dense fogs are encountered off the
coast north of the 35th parallel. The storm is losing a little of its
tropical intensity, but its area is increasing and winds of hurricane
force are raging over a vast area between Hatteras and Bermuda.]
[Illustration: _Sept. 9_.--The storm is still raging with great
violence between Nantucket, Hatteras, and Bermuda. Tremendous seas and
tides are driving in on the coast. It is blowing with hurricane force
close in shore near Hatteras. The storm-center is still moving
northward, but more slowly, and the great area of high barometer into
which the hurricane has forced its way stands fast, the pressure rising
to 30.30 over the Gulf of St. Lawrence and the isobar of 30.00 reaching
south on either side well down toward the tropics. To the
northwestward, northward, and northeastward, close to the outer limits
of the great whirlwind, warm, sultry weather prevails, with calms or
light, variable winds, hazy weather, and barometer above the normal.]
[Illustration: _Sept. 10_.--The hurricane seems to be gathering all its
strength for a last desperate struggle to force its way along its
normal track to the northeast. The wind-arrows plotted on the Chart
illustrate very graphically the marked circular character of the great
whirlwind. The storm-wave, or general elevation of the oceanic surface
caused by the in-rushing and whirling winds, and the reduced barometric
pressure (acting as a partial vacuum), bank up the water in the bight
of the coast about Sandy Hook, and cause the greatest floods on record
at many places along the eastern coast of New Jersey and the southern
shore of Long Island.]
[Illustration: _Sept. 11_.--The barometric pressure at the storm-center
has increased noticeably. The low area is filled up, and the barometric
gradients are very much less steep. Very few winds of full hurricane
force are reported. The storm-center has moved in toward shore,
however, and stormy winds are still felt along the coast. The clouds
are breaking away in places, and the cyclonic circulation is no longer
so well marked. The warm waters of the Gulf Stream have been driven in
toward the coast off Block Island by the long-continued and furious
southeasterly gales on the right of the storm track, and, mingling with
the cold in-shore current, cause dense fogs and squally, unsettled
weather.]
[Illustration: _Sept. 12_.--The great hurricane has blown itself out,
and although a few reports still give a force of wind as high as 10 of
Beaufort's scale, the storm has practically ended. The remnants drift
inland during the 13th and 14th, with cloudy, rainy weather in eastern
Virginia and Maryland. It leaves a mountainous cross-sea that lasts for
several days, a coast line strewn with wreckage and already some twenty
additions have been made to the list of derelicts and drifting wrecks
whose positions are plotted on the Pilot Chart as a caution to
navigators. How many vessels it wrecked at sea can never be fully
known, but its entire track is marked by wrecks and wreckage.]}
The importance to navigators of a true appreciation of the law of
storms--not the mere memorization of a set of rules, but an intelligent
comprehension of the subject--is now perhaps clearly evident to the
reader: at any rate, that is the object I have aimed at, rather than a
mere formal statement of generally accepted principles and an abstruse
discussion of isobars and gradients.
It will be seen that _the probable bearing of the center, as indicated
by the direction of the wind at a single station_, is the great
question, so far as the navigator is concerned. There are men who want
and must have a hard-and-fast rule,--an 8-point, a 10-point, or a
12-point rule--something to act on without thought, while every nerve
is strained to save the ship's spars, sails, boats, engines, and cargo,
from damage or destruction. Under such circumstances, I think that
perhaps the safest general plan is to use the old 8-point rule, but
_applied to the low clouds, instead of to the wind_. This is
equivalent, generally speaking, to a 10-point rule, applied to the
wind. That any such rule, if intended for general application, is only
roughly approximate, goes without saying, or ought to do so, at least.
The angle of bearing changes in different parts of the storm, it varies
with the quadrant, with the latitude, with different storms, and with
various other conditions, too numerous to be mentioned or even wholly
known. One good general rule is that in rear of a hurricane the wind
blows somewhat decidedly toward it; and yet that there are marked
exceptions is well illustrated by the chart of the hurricane of
November 25, 1888, already referred to. As a good example of the wind
circulation in a hurricane in the tropics the accompanying diagram is
of interest. This represents two days (the 3d and 5th) of the great
Cuban hurricane of September, 1888, the intervening day (September 4th)
being omitted, for the sake of clearness. Its severity is sufficiently
indicated by the fact that it caused the loss of fully a thousand lives
in Cuba, and destroyed property of the estimated value of $5,000,000 in
the single province of Sagua. Now take any point on any one of these
spiral lines, and observe the bearing of the center: in rear of the
storm, especially, the 8-point rule is hardly applicable, and action
based upon it might result disastrously.
[Illustration: The Cuban Hurricane of September, 1888, illustrating the
surface wind-circulation on September 3d and 5th, at noon, Greenwich
mean time.]
The next and last plate, entitled,
HURRICANES IN THE NORTH ATLANTIC.--TYPICAL CIRCULATION OF THE WIND,
FROM ACTUAL OBSERVATION,
gives a still more complete illustration of the wind-circulation in
hurricanes, with a brief discussion of the application of the 8-point
rule. Especial attention is called to the statement made thereon
(referring, of course, to hurricanes in the North Atlantic, but no
doubt true for the entire Northern Hemisphere) that
"although the 8-point rule is nearly true when the wind is anywhere
from north to south by way of west (that is, generally speaking, in the
navigable semicircle), it is liable to be a very poor guide when the
wind is from any point in the first or second quadrant."
Also to the following, which is applicable to the Southern Hemisphere
by the substitution of "to the left" for "to the right:"
"Perhaps the best general rule is that the center bears about eight
points to the right of the direction from which the low clouds come,
or, what is practically the same thing, eight points to the right of
the wind at the moment of a sudden shift in a heavy squall; after such
a shift the wind will remain steady in direction for a time, but the
center is meanwhile moving along and the angle of bearing changes until
the next shift, when it goes again to eight points, and so on."
Such diagrams, carefully prepared from complete and reliable data, are
of far greater practical value to navigators than volumes of
explanation: they appeal to the eye and will live in memory long after
ideas conveyed by printed words have been forgotten.
{PLATE: HURRICANES IN THE NORTH ATLANTIC.--TYPICAL CIRCULATION OF THE
WIND, FROM ACTUAL OBSERVATION. [From the Pilot Chart of the North
Atlantic Ocean, July, 1890.]
The above diagrams have been prepared from a large number of
observations in order to illustrate the actual circulation of the wind
in hurricanes, as a practical guide for navigators during the present
hurricane season. The small chart that was presented on the Pilot Chart
last month gave all the observations upon which the spiral lines were
based for that particular hurricane (Nov. 25, 1888), and the same
method has been followed here, only the observations themselves are
omitted, for the sake of clearness. Perhaps the most important point to
notice is that the surface wind blows in an inward spiral curve, and
not circularly, except very near the center. The center therefore
generally bears more than eight points to the right of the wind.
Another very important point is the fact that although the 8-point rule
is nearly true when the wind is anywhere from _North to South by way of
West_ (that is, generally speaking, in the navigable semicircle), it is
liable to be a very poor guide when the wind is from any point in the
first or second quadrant. With the wind from NE., for instance, the
center may bear anywhere from South to SE.; with the wind East it may
bear from SW. to South; and with the wind SE. it may bear SW., West, or
even (in the tropics) W NW. Perhaps the best general rule is that the
center bears about eight points to the right of the direction from
which the low clouds come, or, what is practically the same thing,
eight points to the right of the wind at the moment of a sudden shift
in a heavy squall; after such a shift the wind will remain steady in
direction for a time, but the center is meanwhile moving along and the
angle of bearing changes until the next shift, when it goes again to
eight points, and so on.
It will be noticed that the northernmost of these two hurricanes was
moving very slowly during the two days selected for illustration: had
it been moving faster, the in-draught (or departure from the circular
direction) would no doubt have been somewhat less in advance and
considerably greater in rear than what is indicated. It is exceptional
also to find a storm in this region growing smaller, as this seems to
have done on Sept. 10th; it died out altogether in a few days, instead
of continuing its motion toward E NE., as is usually the case. In the
tropics the usual progressive motion is about W. by N., and this,
together with the steady increase in size, is well illustrated in the
case of the Cuban hurricane; it should be noted, however, that the
interval is here two days, and not one, as in the upper diagram.
Masters of vessels are earnestly requested to keep regular observations
for this Office during the hurricane season, even if only position,
wind, weather, and barometer, at noon, G. M. T., are noted. A single
additional report often adds greatly to the completeness of the data
used in preparing these diagrams.}
Finally, let us look for a moment at two sketches that I have made to
give a graphic and I hope not incorrect idea of the cloud formation and
the internal structure of a hurricane. In both sketches the vertical
scale is of course greatly exaggerated. The first illustrates
particularly the great cloud bank (with the "bull's eye," or clear
central space, shown in cross-section); the storm-wave or general
elevation of the surface of the ocean caused by the spirally in-blowing
winds and low barometric pressure (the cause, oftentimes, of fearful
floods along low-lying coasts); and the probable, or possible,
circulation of the upper atmosphere over the whirl, together with the
direct and reflected rays of a vertical sun as they pour into the
central calm. The second sketch is to aid a clear mental conception of
the actual motions of the particles of air as they flow inward below,
whirl about the central core and flow outward above; this may help to
free the mind from an erroneous idea that may be suggested by thinking
of or seeing the enormous, piled-up, apparently stationary mass that
constitutes the _barra_, or cloud-bank of the hurricane, but which is
really only the stationary and visible _locus_ where the conditions are
such that the whirling, rushing masses of humid atmosphere condense
their tons of aqueous vapor and leave it, as they pass upward and
outward. It is analogous to the cloud-cap, or banner, that hangs
stationary over a lofty mountain peak, although if you visit the peak
you may there find a living gale of wind.
[Illustration: Sketch, in cross-section, to illustrate the
cloud-formation, storm-wave, etc., in a hurricane. The dotted lines
represent the probable circulation of the upper atmosphere.]
[Illustration: Sketch, in perspective, to illustrate graphically the
lower-atmosphere-wind-circulation in a hurricane. The inward spiral at
the base is the surface wind.]
In both of these sketches my object has been to try to convey an idea
of the marked individuality, symmetry, and intensity of a tropic
cyclone, and its grasp upon and intimate connection with the ocean,
which it joins to the upper atmosphere by a huge, hollow trunk, with
widely extended roots and spreading branches,--no doubt an enormous and
effective conductor of atmospheric electricity, too, whose power is
quickly shattered and destroyed by contact with the land; the notable
absence of thunder (illustrated by the report of the "Victoria," quoted
above) is of interest in this connection. If I have succeeded in this,
and thereby given a clearer idea to the casual reader or suggested a
fertile train of thought to any physicist, I shall feel more than
repaid for the effort.
I have thus attempted little more than to touch upon the practical side
of this great question, and this in a popular way, to induce my readers
to follow me to the end. The many other interesting questions that
might be raised and discussed must here be left untouched. Our efforts
in the Hydrographic Office must be primarily to help the navigator, and
only secondarily to try to collect and publish facts for the scientist
to study at his leisure. The causes of these terrific storms are of
interest to us as they may help us to predict their coming, rather than
for the proof of any theory, or the gratification of any pet idea. And
if Science will but improve the Law of Storms, as practical men use it
for the guidance of their vessels and the safety of the lives and
cargoes intrusted to their care, it will be one more welcome proof that
theory and practice go hand in hand.