XVI TABLES AND RESULTS OF THE PRECIPITATION OF RAIN AND SNOW IN U. S. 



such as is covered by a city of moderate extent ; the results here collected give 

 abundant proof, not only of large differences in the amount collected in single 

 showers, in consequence of their not unfrequently sharp definition of extent, but also 

 in the aggregate monthly and annual amounts. There are a few records of western 

 stations which, in some parts, leave it doubtful whether a blank indicates that no 

 rain fell or whether no observations were made ; not to introduce any uncertainty 

 ill the deductions and in the absence of better information in such cases, it was 

 assumed that no observations were taken. A more embarrassing case to the com- 

 puter was the uncertainty, in many instances, whether melted snow had been 

 included by the observer in his result or not. This question was not unfrequently 

 difficult to decide, but, upon the whole, the discussion of the annual periodicity of 

 the rain gave sufficient proof that no serious error has crept into the results from 

 that source of defective information. No results at stations, when such omissions 

 were known to exist, were admitted in the discussion. 



The following tables, A and B, show the average amount of precipitation for 

 each month, season, and year, and the amounts for a series of years, in the United 

 States, some adjacent parts of North America, and in Central and South America. 

 They have been, as previously stated, deduced from the manuscript tables retained in 

 the Smithsonian Institution for future use and reference. 



