MADE AT BRUNSWICK, MAINE 



45 



4 



From the annual amounts set out in the above table a probable uncertamty of 



455 2A' 



= ± 1.5 inches in the average annual amount may be deduced. 



n (n — 1) 



The maximum amount of rain in any one day vpas 8.25 inches on November 4, 

 1845 ; the next heaviest fall of rain occurred on August 11th, 1843, of 7.70 inches ; 

 on the 27th of May, 1850, 7.10 inches feU. 



On the 10th of March, 1819, 30 inches of snow fell; on December 28th, 1848, 

 20 inches; in 1809, January 30th, 1811, February 4th, and 1823, September 17th, 

 18 inches of snow are recorded during a day. ■* 



The probable uncertainty of the annual average value from a series extending 

 over 32 \ years is yet "sufficiently large to mask the annual fluctuation to an extent 

 which renders it difficult to recognize the maxima and minima with certainty. 

 We may here use with advantage the results of two stations in the same hyetal 

 region, given in the Army Meteorological Register (Washington, 1855). At Fort 

 Preble, near Portland, the mean annual precipitation from a series of eight and a 

 half years is 45.25 inches, and at Fort Constitution, near Portsmouth, from a series 

 of thirteen years, 35.57 inches. We find that the annual fluctuation attains two 

 maxima and two minima, the former in May and November, the latter in February 

 or March and in September. The November maximum of precipitation and the 

 February or March minimum are the most prominent features. 



On the average there are 64 rainy days and 30 snowy days each year, or 94 days 

 of precipitation, being 1 in 4 nearly. The average amount of water for a day is 

 ^ = 0.48 inches. The corresponding monthly means are contained in the follow- 

 ing table: — 





From 



From 



Average 





From 



From 



Average 





Table XIII; 



Table XIV. 



in one day. 





Table XIII. 



Table XIV. 



in one day. 



January . . . 



90.5 



Si^.a 



0'°.33 



July 



1M 



3'-. 6 



0'°.51 



February . . . 



8.0 



2.7 



0.34 



August .... 



6.7 



4.4 



0.65 



March .... 



8.7 



3.7 



0.42 



September . . . 



5.9 



3.0 



0.51 



April .... 



7.4 



3.4 



0.46 



October .... 



6.8 



3.7 



0.54 



May 



8.8 



4.5 



0.51 



November . . 



8.4 



4.6 



0.55 



June 



7.3 



3.7 



0.51 



December . . . 



9.0 



3.8 



0.42 



The heaviest rains therefore fall in August, the lightest in January and February, 

 epochs at which the air's capacity for vapor is greatest and least. 



Relation of Rain {or Snoiv) to the Direction of the Wind. 



To ascertain the dependence of rain (or snow) on the direction of the wind, the 

 latter was tabulated for each rainy day and classified according to seasons. Such 

 days only were used on which rain^ (or snow) is recorded morning, noon, and eve- 

 ning, except for summer, when days with two consecutive entries of rain were 

 included in order to obtain the requisite number of cases. The total number of 

 directions thus classified on such rainy days during 51 years is 2756, of which 

 occurred in spring 662, in summer 545, in autumn 596, and in winter 953. 



* Days with two entries of rain (or snow) and the third entry of sleet, hail, mist, or fog were also 

 included. 



