44 National Geographic Magazine. 



front line of this advancing battalion of cold northwesterly winds 

 is more than a thousand miles in length, and covers the whole 

 breadth of the United States : its right flank is on the Gulf, its 

 left rests on the Great Lakes, or even farther north ; the tempera- 

 ture falls rapidly at its approach, with frost far south into Louis- 

 iana and Mississippi, and heavy snow in central Kentucky and 

 eastern Tennessee, The long swaying line is advancing toward 

 the coast at the rate of about 600 miles a day, followed by a 

 ridge of high barometer reaching from Texas to Dakota and 

 Manitoba. At points along the trough the barometer ranges 

 from 29. 70, a hundred miles north of Toronto, to 29.86 at Pitts- 

 burg, 29.88 at Augusta, and 29.94 at Cedar Keys. Along the 

 ridge the barometer is very high ; 30.7 to the northward about 

 Lake Winnipeg, 30.6 in Wyoming, 30 7 in Indian Territory, and 

 30.5 south of the Rio Grande. The difference of pressure from 

 trough to ridge is thus measured by about an inch of mercury in 

 the barometer. Moreover, the chart shows that there is another 

 ridge of high barometer in advance, curving down ojffi the coast 

 from northern Newfoundland, where the pressure is 30.6, toward 

 Santo Domingo, where the pressure is 30.3, and passing midway 

 between Hatteras and Bermuda. Farther to the eastward the 

 concentric isobars show the presence of a storm which originated 

 about Bermuda on the 9th, and is moving off toward Europe 

 where, in a few days, it may cause northwesterly gales with snow 

 to the northward of its track, and southeasterly gales with rain 

 to the southward. Storm reports from various vessels show that 

 this storm was of hurricane violence, with heavy squalls and high 

 seas, but it need not be referred to in this connection further 

 than to say that it sent back a long rolling swell from northeast, 

 felt all along the Alantic sea-board the morning of the 11th, and 

 quite distinct from that caused by the freshening gale from the 

 southeast. 



Meteorological Conditions Off the Coast. 



While this trough of low barometer, with all its attendant 

 phenomena, is advancing rapidly eastward toward the Atlantic, 

 and the cold wave in its train is spreading over towns, counties 

 and states — crossing the Great Lakes, moving up the Ohio valley, 

 and extending far south over the Gulf of Mexico— we may pause 

 for a moment to consider a factor which is to play a most im- 

 portant part in the warfare of the elements so soon to rage with 



