E. Loomis — Contribution* to M>t<<>rology. 9 



the same time there prevailed in the northeast portion an area 

 of rain of less depth but of equal, or greater, geographical 

 extent, apparently indicating that a small depth of rain in the 

 northern portion of the United States exerts an influence upon 

 the center of low pressure, stronger than that exerted by a 

 greater depth of rain in the southern portion. 



We also find four cases in which the principal rain-center 

 was northwest of the low center. In three of these cases the 

 low center advanced towards the northwest. In the other case, 

 although there was a station on the west side where the rain- 

 fall was 0-07 inch greater than at any station on the east side, 

 the rain-area on the east side was much the greatest in geo- 

 graphical extent, and the area of low pressure moved slowly 



We thus learn that for the whole period of thirty-seven 

 months, during great rain storms, the principal rain-center was 

 most frequently situated nearly in the direction of the average 

 progress of the low centers. The average direction of the 

 storm tracks in column six of the table on page 2, is 15° north 

 of east; which corresponds pretty nearly with the direction in 

 which the principal rain-centers were most frequently found. 

 This coincidence indicates an intimate connection between the 

 rain-fall and the direction of a storm's progress. If however 

 we make the comparison for each case separately, we find 

 anomalies which appear to indicate either that the stations of 

 observation are too distant from each other to show satis- 

 factorily the form and position of the rain-areas, or else the 

 direction of a storm's progress is influenced by other circum- 

 stances than the amount of rain- fall. 



From an examination of columns eight and nine of the 

 table on page 2, we see that the movement of a center of low 

 pressure is attended by a fall of the barometer in front of a 

 storm and a rise of the barometer in its rear ; the average fall in 

 front for these seventy-four cases being 0*23 inch in eight 

 hours, and the average rise in the rear being ( 



low center, and in these cases the rise in the i 

 than the r 



i this statement, for i 



erally a rise of temperature in front of each storm, and a fal 

 temperature in the rear, the average change of temperatun 

 one day from these seventy-four cases being 5° in front and 



