222 



NINTH ANNUAL REPORT OF 



TABLE XV L 



MEAN DIURN'AL VARIATION OF THE CALCULATED FORCE OF VAPOR AT PHILADELPHIA. 



Computed frmn the observations made in 1842, and from July 1, 1843, to July 1, 1845. 



Minimum. 



Maximum. 



TABLE XVII. 



MEAN DIURNAL VARIATION OF ATMOSPHERIC PRESSURE, BAROMETER REDUCED, AT PHILADA 



Computed from the observations made in 1842, and from July 1, 1843, to July 1, 1845. 



1 P. M. 2p. m. 



3 p.m. 



29.927 29.91629.910 29.909 29.911 



4p.m, 



5p.m. 



6p. m, 



29.918 



7 p.m. 



8 P.M. 



9 p.m. 10 a. m. 



29.927 29. 935:29. 943| 29.946 29.949 29.941 



11 A. M. 



12 NIGHT 



Minimum. 



4- 

 Maximum. 



Table XVII shows two maxima and two minima in the height of the 

 barometer, which correspond very nearly in time with those of table 

 VIII for Greenwich. 



