The deepening of the depression is well illustrated by the fact that the lowest reading of the barometer at 7 A.M. was 29.88, at Augusta, Ga.; at 3 P.M., 29.68, at Wilmington, N. C.; at 11 P.M., on board the "Andes," 29.35; and at 7 A.M., the following morning it was as low as 29.20,—an average rate of decrease of pressure at the center of very nearly .23 in eight hours, and a maximum, from reliable observations, of .33.
MARCH 12TH, 13TH, AND 14TH.
The Weather Chart for 7 A.M., [March 12th], shows the line, or trough, with isobars closely crowded together southward of Block Island, but still of a general elliptical shape, the lower portion of the line swinging eastward toward Bermuda, and carrying with it violent squalls of rain and hail far below the 35th parallel. The high land of Cuba and Santo Domingo prevented its effects from reaching the Caribbean Sea, although it was distinctly noticed by a vessel south of Cape Maysi, in the Windward channel, where there were three hours of very heavy rain, and a shift of wind to NW by N. The isotherm of 32° F. reaches from Central Georgia to the coast below Norfolk, and thence out over the Atlantic to a point about one hundred miles south of Block Island, and thence due north, inshore of Cape Cod, explaining the fact that so little snow, comparatively, fell in Rhode Island and southeastern Massachusetts; from about Cape Ann it runs eastward to Cape Sable, and farther east it is carried southward again by the northeasterly winds off the Grand banks. These northeasterly winds are part of the cyclonic system shown to the eastward of this and the preceding chart; farther south they become northerly and northwesterly, and it will be noticed that they have now carried the isotherm of 70° below the limits of the chart. Thus this chart shows very clearly the positions of warm and cold waves relative to such cyclonic systems: first there is this cool wave in rear of the eastern cyclonic system, then a warm wave in front of the system advancing from the coast, and finally a cold wave of marked intensity following in its train.
It was probably during the night of the 12th that the lowest barometric pressure and the steepest gradients occurred. Although several vessels report lower readings, yet a careful consideration of all the data at hand indicates that about the lowest reliable readings are those taken at 10 P.M. at Wood's Holl, Mass. (28.92), Nantucket (28.93), Providence, R. I. (28.98), and Block Island (29.00). The steepest barometric gradients, so far as indicated by data at hand, are also those that occurred at this time, and are as follows, taking Block Island as the initial point and distances in nautical miles: at New London, 26 miles, the barometer stood 29.11, giving a difference of pressure in 15 miles of .063 inch; New Haven, 62 miles, 29.36, .087; New York, 116 miles, 29.64, .083; Albany, 126 miles, 29.76, .090. At 7 A.M. the following day, very low readings are also reported: New Bedford, Mass., 28.91, Block Island, 28.92, and Wood's Holl, 28.96.
The chart for 7 A.M., [March 13th], shows a marked decrease in the intensity of the storm, although the area over which stormy winds are blowing is still enormous, comprising, as it does, almost the entire region charted. From the Great Lakes and northern Vermont to the northern coast of Cuba the wind is blowing a gale from a direction almost invariably northwest, whilst westerly winds and low temperatures have spread over a wide tract of ocean south of the 40th parallel. North of this parallel, the prevailing winds are easterly, the isobars extending in a general easterly and westerly direction. At the storm center off Block Island the pressure is 28.90, but the gradients are not so steep as on the preceding chart, and the severity of the storm, both ashore and at sea, has begun to diminish. About this center, too, the isobars are noticeably circular in form, showing that, although it first formed as an elliptical area, it gradually assumed the character of a true revolving storm, remaining almost stationary between Block Island and Nantucket until it had actually "blown itself out," while the great storm of which it was a conspicuous but not essential part was continuing its eastward progress. The enormous influx of cold air brought down by the long continued northwesterly gale is graphically shown on this chart by the large extent and deepening intensity of the blue tint, where the temperatures are below the freezing point. From the northwestern to the southeastern portion of the chart we find a difference in temperature of more than 80° F. (from below –10° to above 70°); the steepest barometric gradient is found to the northwest of Block Island, where the pressure varies 1.80 inches in 750 miles (gradient, .036 inch in 15 nautical miles), and .66 inch in 126 miles (Block Island to Albany, N. Y.; gradient, .079).
On the chart for 7 A.M., [March 14th], the depression off Block Island has almost filled up, and the stormy winds have died out and become light and variable, with occasional snow squalls. The other storm center has now regained its ascendency, and is situated about two hundred miles southeast from Sable Island, with a pressure about 29.3. The great wave of low barometer has overspread the entire western portion of the North Atlantic, with unsettled squally weather from Labrador to the Windward Islands. The area of high pressure in advance has moved eastward, to be felt over the British Isles from the 17th to the 21st of the month, followed by a rapid fall of the barometer as this great atmospheric disturbance moves along its circuit round the northern hemisphere. The isotherm of 32° is still south of Hatteras, reaching well out off shore, and thence northward, tangent to Cape Cod, as far as central Maine, and thence eastward to St. Johns, Newfoundland. Great contrasts of temperature and pressure are still indicated, but considerably less marked than on the preceding chart, and the normal conditions are being gradually restored.
CONCLUSION.
The great storm that has thus been briefly described, as well as can be done from the data now at hand and in the limited time at our disposal, has furnished a most striking and instructive example of a somewhat unusual class of storms, and this on such a grand scale, and in a part of the world where the data for its study are so complete, that it must long remain a memorable instance. Instead of a more or less circular area of low barometer at the storm center, there is here a great trough of "low" between two ridges of "high," the whole system moving rapidly eastward, and including "within the arc of its majestic sweep," almost the entire width of the temperate zone. The "trough phenomena," as an eminent meteorologist has called the violent squalls, with shifts of wind and change of conditions at about the time of lowest barometer, are here illustrated most impressively. Such changes are, of course, to be expected and guarded against in every storm, and sailors have long ago summed them up, to store away in memory for practical use when occasion demands, in the well-known lines,—
| "First rise after low Indicates a stronger blow." |
One thing to which attention is particularly called is the fact that storms of only ordinary severity are likely, upon reaching the coast, to develop greatly increased energy. As has been already pointed out, there can be no doubt but that this is especially so in a storm of this kind, where the isobars are elongated in a north and south direction. The accompanying [Barometer Diagram], if studied in connection with the [Track Chart] and the Weather Chart for [March 11th], illustrates very clearly this deepening of the depression at the storm center. The formation and persistency off Block Island of a secondary storm center of such energy as was developed in this case, however, it would seem wholly impossible to have foretold, and a prediction to that effect made under similar circumstances would probably prove wrong in at least nine cases out of ten. But it may be safely said that the establishment of telegraphic signal stations at outlying points off the coast is a matter of great importance, not only to our extensive shipping interests, but to the people of all our great seaboard cities as well. To the northward, telegraphic reports from such stations would furnish data by which to watch the movement of areas of high barometer, upon which that of the succeeding "low" so largely depends; and to the southward, to give warning of the approach and progress of the terrific hurricanes which, summer after summer, bring devastation and destruction along our Gulf and Atlantic coasts, and of which this great storm is an approximate example and a timely reminder. In this connection, also, there is another important result to be gained: scientific research and practical inventive genius, advancing hand in hand for the benefit of mankind, have discovered not only the laws governing the formation of the dense banks of fog that have made the Grand Banks dreaded by navigators but also the means by which certain facts may be observed, telegraphed, charted, and studied a thousand miles away, and the occurrence of fog predicted with almost unfailing accuracy, even whilst the very elements themselves are only preparing for its formation. By means of such predictions, the safety of navigation along the greatest highway of ocean traffic in the world would be vastly increased,—routes traversed yearly at almost railway speed by vessels intrusted with more than a million human lives, and property of an aggregate value of fully a billion dollars. What is everybody's business is too often nobody's business, and if no single nation is going to undertake this work, an international congress should be formed to do so, with full authority to act and power to enforce its decisions.