18 E. Looinlx—Contr'thiit'.nnH ?<> Meteorology. 



We see from this table that in a period of twenty-one 

 months, there were thirty -six cases in which a total rain-fall of. 

 ihes in eight hours was followed by a total rain-fall of 

 more than rive inches during the next eight hours ; there were 

 twenty-five cases in which it was followed by a similar rain- 

 fall during a third period of eight hours ; there were sixteen 

 cases in which it was followed by at least four and a half inches 

 of rain during a fourth period of eight hours ; there were ten 

 cases of a fifth period ; seven cases of a sixth period ; four 

 cases of a seventh period ; three cases of an eighth period ; and 

 one case of a tenth period. These rain areas which succeeded 

 each other in order of time, were not however in all cases con- 

 tinuous rain areas, nor were they even adjacent to each other. 

 Those cases which were apparently thus related as forming 

 continuous rain -areas, ate indicated by the numerals 1, 2, 3, 

 etc., attached to the names of the stations. We find that out 

 of these thirty-six cases there were only fourteen cases in which 

 the same rain-area continued for as much as three periods of 

 eight hours; and in only seven cases did the same rain -area 

 continue for more than three periods; that is, more than 

 twenty-four hours. 



We thus see that in the United States, rain areas, with a fall 

 of at least a half inch in eight hours, seldom continue for more 

 than twenty-four hours. This result accords very closely with 

 that deduced in my seventh paper from observations of sixteen 

 months. During "the entire period of the published observa- 

 tions (thirty seven months) we find only nine cases in which 

 the same rain-area, with a fall of at least a half inch in eight 

 hours, continued longer than one day. making on an average 

 three cases in a year, derived from a comparison of all the 

 cases in which there was a total rain-fall of at least nine inches 

 in eight hours at ninety stations. This result has an important 

 bearing upon the philosophy of storms. It was objected to 

 Espy's theory of storms that if his computations were correct, 

 when rain had once commenced it would have the power of 

 perpetuating itself ; that is, it should be a veritable perpetual 

 motion, and should never cease. The comparison of three 

 years' observations however shows us that although consider- 

 able rain attends all great storms, or areas of low barometer, 

 and these areas of low barometer can sometimes be traced 

 through a distance of many thousand miles, yet the rain -fall 

 in such a storm does not form a regular rain-belt of many 

 thousand miles in length and of nearly uniform breadth, but 

 rather a succession of rain areas grouped irregularly together. 

 The continuity of the belt may not be absolutely broken, but 

 its breadth and density exhibit great irregularities. While a 

 storm is pursuing its path from the Rocky Mountains to the 



