150 



REPORT 1839. 



3rd, The mean pressure of different seasons, including 

 spring, summer, autumn and winter, and of summer and win- 

 ter in periods of six months each. 



4th, The course of the atmospheric tides in different seasons, 

 and the times of the day when the mean pressure occurs in 

 each. 



5th, The average monthly pressure and periods of the year 

 at which the mean pressure occurs. 



6th, The relation between the mean pressure of the twenty- 

 four hours, and that of any given hour or pair of hours. 



3. Table I. Plate V. 



Containing the Mean Hourly Pressures for each of the Years 

 1837, 1838, 1839, together with the Mean of these years ; 

 from 26,280 observations, at 75 feet above the mean level of 

 the sea, reduced to 32° of Fahrenheit's scale. 



The periods of maxima are denoted by the sign + , the minima 

 by the sign — , and the mean by a *. 





1837. 



1838. 



1839. 



Mean ofthe 3 years 



A.M. I 



29-8719 



*29-7565 



#29-7768 



29-8017 



2 



^29-8696 



29-7547 



29-7735 



*29-7993 



3 



29-8626 



29-7518 



29-7688 



29-7944 



4 



29-8608 



29-7507 



29-7670 



29-7928 



5 



-29-8606 



-29-7507 



-29-7670 



-29-7928 



6 



29-8619 



29-7552 



29-7710 



^29-7960 



7 



29-8666 



#29-7585 



29-7755 



29-8002 



8 



*29-8706 



29-7615 



*29-7772 



29-8032 



9 



29-8717 



29-7637 



29-7790 



29-8048 



10 



-J- 29-8732 



+29-7645 



+29-7807 



+29-8061 



11 



29-8720 



#29-7627 



29-7788 



29-8045 



12 



^29-8663 



29-7587 



29-7755 



29-8002 



P.M. 1 



29-8627 



29-7540 



*29-7705 



29-7957 



2 



29-8580 



29-7517 



29-7670 



29-7922 



3 



29-8567 



29-7500 



29-7657 



29-7908 



4 



-29-8558 



-29-7475 



-29-7652 



-29-7895 



5 



29-8597 



29-7532 



29-7685 



29-7938 



6 



29-8629 



#29-7557 



29-7725 



29-7970 



7 



,29-8679 



29-7610 



29-7770 



*29-8019 



8 



29-8740 



29-7645 



*29-7798 



29-8061 



9 



29-8779 



29-7672 



29-7832 



29-8094 



10 



+29-8792 



+29-7665 



+29-7840 



+29-8099 



11 



29-8790 



29-7665 



29-7822 



29-8092 



12 



29-8783 



29-7639 



29-7775 



29-8065 





29-8675 



29-7579 



29-7743 



29-7999 



Note. — The * indicating the Mean Pressure is placed between the hours at 

 which the mean occurs when the mean does not correspond to the pressure of 

 either. 



