H. A. Rowland — Studies on Magnetic Distribution. 17 



Stationary Storms. 



When a storm center has crossed the United States and 

 passed to Nova Scotia or Newfoundland, we often find on the 

 United States Weather Maps for two or three subsequent days 

 the word low on the northeast corner of the maps, seeming to 

 indicate that the center of the storm remained during that pe- 

 riod nearly stationary. The Danish maps (from Dec, 1873, to 

 Aug., 1874,) show us that storms do sometimes remain nearly 

 stationary for several days. 



Case I From the 5th to the 8th of March, 1874, a violent 

 storm moved from New Mexico to the St, Lawrence valley. 

 On the 9tli the center of this storm was a little north of Hali- 

 fax ; on the 10th it was still near the same place ; on the 11th 

 it had moved northeast nearly 400 miles ; on the 12th it had 

 moved south about 200 miles ; on the 13th it had moved north 

 about 200 miles ; on the 14th it had moved south about 200 

 miles ; and on the 15th it moved northeast about 700 miles. 

 Thus during five days (March 9-14) the center of the storm 

 had advanced less than 350 miles, being an average motion of 

 less than three miles an hour, and during the first four days 

 the barometric depression was greater than it was on the 8th. 



Case II. From April 26th to 30th, 1874, a storm moved 

 across the United States from Colorado to the St. Lawrence 

 valley. During the next day (May 1st) the storm was station- 

 ary ; on the 2d it moved a little to the southeast ; on the 3d it 

 moved a little to the east ; and on the 4th it reached St. Johns, 

 Newfoundland. Thus in four days the center moved 775 miles, 

 being an average rate of about eight miles an hour ; and 

 during the first half of this time the average movement 

 scai'cely exceeded four miles an hour. 



In preparing the materials for this article, I have been as- 

 sisted by Mr. Edward S. Cowles, a graduate of Yale College of 

 the class of 1873. 



-Studies on Magnetic Diatribution ; by 

 ~ ■ " lity, Ba 



KowLAND, of the Johns Hopkir 



Let us now consider the case of that portion of the bar which 

 is covered by the helix. First of all, when the helix is symmet- 

 rically placed on the rod, equations (5) and (6) will apply. 

 As Q'^e is the quantity which is usually taken to represent 



AM. .JouH. Scl-Third Sbries, Vol. XI, No. 61.- Jan., 1876. 



