164 



REPORT 1839. 



it will be seen that the greatest deviations occurred in October 

 and November, and the least in March. 



Table XVIII. 

 Showing the Deviations of the Mean Monthly Pressure for the 

 Mean for the Years 1837, 1838, 1839, reduced to 32° of 

 Fahrenheit. 



Jan. 



Feb. 



March. 



April. 



May. 



June. 



July. 



August. 



Sept. 



Oct. 



Nov. 



Dec. 



+•062 



-•055 



f^OOl 



+•035 



+•034 



-•012 



+•040 



+•057 



-•094 



+•129 



-•203 



-•002 



The months of March and December, therefore, approach 

 nearest the mean, whilst the maximum and minimum occur in 

 October and November. 



The recurrence of the mean pressure four times in the 

 twenty-four hours at once points out the hours, or pairs of 

 hours, which would be most likely to give the mean pressure of 

 the twenty-four, since it would occur either at the stated hours 

 themselves, or between those falhng on different sides of them. 



In the following table will be found the deviation of each 

 hour from the mean, and in the next table the pairs of hours, 

 the mean pressure of which approach nearest the mean of the 

 whole twenty-four. 



Table XIX. 



Showing the Deviation of each Hour from the line of Mean 



Pressure. 



A.M. 



P.M. 



Hours. 



Deviation. 



Hours. 



Deviation. 



1 



•0018 + 



1 



•0042 - 



2 



*-0006 - 



2 



•0077 - 



3 



•0055 - 



3 



•0091 - 



4 



•0071 - 



4 



•0104- 



5 



•0071 - 



5 



•0061 - 



6 



•0039 - 



6 



•0029 - 



7 



*^0003 + 



7 



*^0020 + 



8 



•0032 + 



8 



•0062 + 



9 



•0049 + 



9 



•0095 + 



10 



•0062 + 



10 



•0100 + 



11 



•0046 + 



11 



•0093 + 



12 



*-0003 + 



12 



•0066 + 



By this table it appears, 1st, that the single hours, which 

 give the nearest approximation to the mean, are 7 a.m. and 12 

 at noon, next to these 2 a.m. and 7 p.m. ; 2nd, that the mean 



