United States Weather Maps and other sources. 7 



rain. In searching for observations to test this conclusion, I 

 found a decided diurnal inequality in the rain-fall at Philadel- 

 phia showing a maximum about 6 P. M. and a minimum at 3 

 A. M. The observations made by the United States Signal Sei'- 

 vice did not show any decided 'diurnal inequality, owing, per- 

 haps, to their including only three daily observations. In a 

 series of hourly observations made at seven stations in Great 

 Britain I found evidence of two daily maxima and two daily 



Since the publication of my former article I have found in 

 Kreil's Klimatologie von Bohmen the results of ten years' obser- 

 vations at Prag, lat 50° 6', which show a decided diurnal in- 

 equality, having a maximum about 4 P. M. and a minimum 

 about 7 A. M., with a second maximum which is less distinctly 

 marked. The following table shows the average annual 

 rain-fall at Prag as deduced from observations from 1850 to 

 1859 expressed in Paris lines : 



Balnfall at Prag, Aiistria. 



Hour. 



Kain-fall. 



Hour. 



Eain-fall. 



Midnight. 



6-864 



Noon. 



7-063 









8-901 





5-986 













10-207 





tin 





10-845 





5-049 





8-211 





6-949 







i? 



6-798 

 6-072 



10 



till 



These numbers follow a law bearing a close resemblance to 

 that of the Philadelphia observations, and lead us to presume 

 that a similar law must prevail in the fall of rain over a con- 

 siderable portion of the United States. 



I have received the hourly observations of rain-fall at seven 

 stations of Great Britain complete for the year 1874. At most 

 of the stations there are evidently two periods of maximum 

 rain-fall, but the time of maximum appears to depend very 

 much upon local circumstances. 



Comparison of storm paths in America and Europe. 



In compari 

 :urope I hav 



\ the tracks followed bv i 



) daily United States Signal Service maps from 1871 

 ^ 1875, and especially the monthly maps showing the tracks 



