Page:The National geographic magazine, volume 1.djvu/67

 the retardation of the center of the line, in its eastward motion, by the area of high barometer about Newfoundland; thus this storm center delayed between Block Island and Nantucket while the northern and southern flanks of the line swung around to the eastward, the advance of the lower one gradually cutting off the supply of warm moist air rushing up from lower latitudes into contact with the cold northwesterly gale sweeping down from off the coast between Hatteras and Montauk point. So far as the ocean is concerned, the 12th of March saw the great storm at its maximum, and its wide extent and terrific violence make it one of the most severe ever experienced off our coast.

The deepening of the depression is well illustrated by the fact that the lowest reading of the barometer at 7 was 29.88, at Augusta, Ga.; at 3, 29.68, at Wilmington, N. C.; at 11 , on board the "Andes," 29.35; and at 7 , 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.

The Weather Chart for 7, 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 Aun 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