242 PROGRESS OF METEOROLOGY IN 1889. 



A general storm, central in the Ohio valley on the 30th, passed slowly 

 eastward over the Alleghaiiies in Virginia, where it remained until the 

 evening of the 31st. Its slow movement was attended by conditions 

 favorable to continued heavy rains,— east and southeast winds along the 

 coast, high temperature, and dense saturation. As this saturated con- 

 dition reached the higher ridges of the AUeghanies it developed the 

 most excessive rain-fall of the century for so large an area, depositing a 

 uniform sheet of from G to 8 inches of rain-fall during a continuous 

 storm of from twenty-four to fifty-six hours' duration. This rain-fall 

 was in sheets or masses rather than in drops, being described as "cloud- 

 bursts" by observers in localities from Pennsylvania to Virginia. The 

 intensity of the barometric depression was not large, but on the other 

 hand rather small. At Pittsburgh the fall of the barometer was about 

 one-fourth of an inch only, and the lowest isobars were 29.7 on the 30th 

 and 29.8 on the 31st. 



A table is given containing all the rain-fall observations made in the 

 middle Atlantic States during the period of heavy rains, and approxi- 

 mate isohyetal lines are presented on charts. The times of beginning of 

 rain are not very accordant, but the observations indicate that the prog- 

 ress of rain was from the coast inland, and from the south toward the 

 north. The greatest rain-fall was in the northeast quadrant of the bar- 

 ometric depression, where there was a steep temperature gradient, the 

 temperature increasing from 40<^ in the lake region to 70° on the Atlan- 

 tic coast. 



The floods resulting from these rains extended from southern New York 

 over Pennsylvania, Maryland, and the Virginias, were unprecedented in 

 height, and the most destructive ever occurring in the United States. 

 A detailed statement of the enormous loss of life and property in the 

 flooded region would require more space than is here available. Cities 

 were inundated, bridges swept away, canals washed out, harbor im- 

 provements damaged, and millions of dollars worth of property de- 

 stroyed. As a culmination of these disasters, the dam on the South 

 Fork above Johnstown, Pennsylvania, gave way, and the immense body 

 of water in the reservoir swept down upon that city and adjoining vil- 

 lages, causing the loss of nine thousand lives and thirty million dollars' 

 worth of property. 



Vn.— WINDS AND OCEAN CURRENTS; GENERAL ATMOSPHERIC CIRCU- 

 LATION. 



The Helm wind.— Mr. W. Marriott has presented to the Eoyal Meteor- 

 ological Society a report on the Helm-wind — a wind i^eculiar to the 

 Cross Fell Range of mountains in Cainberland. This range is high, 

 and runs from north-northwest to south-southeast without being cut 

 through by any valley. From the top of the mountains to the plain 

 on the west there is an abrupt fall of from 1,000 to 1,500 feet in a mile 

 and a half. At times, when the wind is from some easterly point, the 



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