220 



NINTH ANNUAL REPORT OF 



According to this table the tension or elastic force of vapor at Bom- 

 bay arrives at its minimum at 6 a. m., and its maximum not until 6 p. 

 m. This difference in the time of the maximum and minumum at 

 Bombay and Greenwich probably arises from the tropical position of 

 the former. 



TABLE XII. 



MEAN DIURNAL VARIATION OF THE BAROMETER AT BOMBAY, 1843. 



This table exhibits, as in the case of that for Greenwich, two maxi- 

 ma and two minima. 



The following tables exhibit the mean diurnal variations in the 

 meteorological elements at Girard College, Philadelphia. They pre- 

 sent the result of the observations for each hour of the 24. 



TABLE XIII. 



MEAN DIURNAL VARIATION OF THE TEMPERATURE OF THE AIR AT PHILADELPHIA. 



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



+ 



Maximum. 



By comparing table XIII with table I, it appears that the diurnal 

 variation of temperature, at Greenwich and Philadelphia, is nearly the 

 same. The minimum occurs a little earlier at the latter, and the maxi- 

 mum a little later. 



