30 



Mr. J. A. Broun on Simultaneous 



[May 11, 



day, instead o£ noon only. Thus the mean of the 24 hours from mid- 

 night of Sunday till midnight of Monday is considered the daily mean 

 at noon of Monday ; that from 1 a.m. of Monday to 1 a.m. of Tuesday 

 is the daily mean at 1 p.m. of Monday ; and so on for each successive 

 hour and for each successive day in the week. These means before and 

 after each turning-point are projected on an enlarged scale (p. 37) ; and 

 from the calculated quantities we shall now seek the hours for which 

 the daily mean atmospheric pressure was a maximum or minimum at each 

 station. 



1. January 7*^, 8*^. Fig. 1, p. 37. This is the first turning-point for 

 all the stations*. "We find from the means shown in this figure : — 



d h 



Highest mean, Simla, January 7 4 

 ,, „ Madras „ 8 4 

 „ „ Singapore ,, 7 12 



2. January 9^ Fig. 2, p. 37. 



d h 



Lowest mean, Simla, January 9 16 

 „ ,, Madras „ 9 17 

 „ „ Singapore „ 9 13 



The next maximum occurs on Sunday, for which there are no observa- 

 tions ; it is easily seen, however, from the curves (p. 28) that this, the 

 principal maximum for the whole period, occurred near January 11*^ 12'* 

 at all the three stations. 



3. January 14<^-16^ Fig. 3, p. 37. 



d h 



Lowest mean, Simla," January 16 5 



„ Madras „ 14 14-20 

 „ ,, Singapore „ 14 12 



It might be supposed that the retardation of the epoch of minimum 

 at Simla was due to the greater descent of the barometer at that station ; 

 but the following maximum, which was also retarded, shows that this was 

 due to some other cause : — 



4. January 16*^-18"^. Fig. 4, p. 37. 



d h 



Highest mean, Simla, January 18 6 ? 



„ Madras „ ' 17 10 



„ „ Singapore „ 16 12 



Here the exact epoch of maximum at Simla can only be estimated from 

 the curves, p. 28, since the barometer was still rising at the last observation 

 on Saturday ; the means for Simla have not been projected, fig. 4. An exa- 

 mination of the curves, p. 28, will show that there can be little doubt as to 



* The observations were not made at Simla in the first week of the year. 



