Maxima and certain Conditions of Temperature, &c. 425 



among which may be the return of the morning wave of pressure. 

 And indeed unless there be such repetition, it is difficult to understand 

 why the rise of pressure sets in so early as between 4 and 5 in the 

 afternoon, instead of between 6 and 7 p.m. ; that is, after the time when 

 the fall is most rapid. And unless the evening wave is repeated in 

 like manner, to explain why the morning rise of pressure begins at 

 least two hours before sunrise. 



Note added August 15, 1888. 



Since the foregoing paper was read before the Society, I have 

 received a table of the mean horary readings of the thermometer, 

 recorded at the Surveyor- General's office, Calcutta, (formerly the 

 Calcutta Observatory) during the same years that have furnished the 

 barometric data, quoted in the text, page 415. They have been computed 

 to hundredths of a Fahrenheit degree, and are as follow — (p. 426). 



The instant of the most rapid rise of forenoon temperature computed 

 from these figures by the method described in the footnote on page 413 

 is as follows in each month : — 





Max. 



rise temp. 



Max. bar. 



Interval. 



January . . . 



. 8h. 



53 m. 



9 



h. 44 m. 



h. 51 m. 



February . . . 



. 8 



46 



9 



52 



1 8 





8 



46 



9 



47 



1 1 





8 



22 



9 



35 



1 13 





7 



54 



9 



23 



1 29 





8 



2 



9 



22 



1 20 



July 



7 



55 



9 



33 



1 38 



August . . . 



. 8 



24 



9 



38 



1 14 



September . 



. 7 



41 



9 



33 



1 52 



October . . . 



7 



44 



9 



25 



1 41 



November . . 



7 



56 



9 



24 



1 28 



December . 



. 8 



56 



9 



34 



40 



Year . . . 



. 8 



27 



9 



35 



1 8 



The variations from month to month shown by this table are, as 

 might be expected, less than in the table at page 415 computed from 

 six years only, but the mean interval for the whole year is exactly 

 the same. 



The irregularity of the evening fall of temperature noticed at 

 page 423 does not appear in the results of this table, and it must 

 therefore remain doubtful whether its occurrence in the three regis- 

 ters quoted in the text is more than a fortuitous coincidence. 



morgens eintreten soil." This objection would be quite valid were the cooling of 

 the atmosphere proceeding at an uniform rate, but not, I think, to the actual facts 

 of the case as above set forth. This was not noticed in my former communication, 

 to which Dr. Sprung refers. 



VOL. XLIV. 2 I 



