1858.] Meteorological Observations on Parisnath Hill. 17 



The mean temperatures of the 2nd have been inserted in the 

 table, merely to show the reason for rejecting the barometrical 

 observations of the hours of 9 h. 15 m. and 10 h. 15 m. a. m. made 

 on that day on the hill. The parallelism of the real mean tempera- 

 tures of these hours with those of the mean curve of the stations 

 clearly indicates that one of the two readings must have been erro- 

 neous. The number of observations on that day is not sufficient to 

 warrant an attempt at correcting them. 



The curve of the 3rd April presents some difficulties, the tempera- 

 tures at 8 and 10 A. M. are equal and both higher than that at 9. 

 This arrangement could not by any means represent the true relation 

 between them. 



There being no direct and certain indications to guide us in 

 selecting one of these temperatures as correct, which might then 

 serve as a starting point in altering the other two, the following 

 considerations decided me at last in favour of the temperature 

 at 9. 



It will be recollected from Table III. that the mean temperatures 

 of the air between the stations for the whole 24 hours, as derived 

 from the thermometric observations (Col. IV.), showed a difference of 

 only 0°.6. Assuming that the real daily mean temperatures of the air 

 on both days would differ rather less than more in the same or the op- 

 posite direction, from each other, and that, judging from observations 

 made by others, they would fall later than the hour at which the daily 

 means had been observed to fall in the curve of the mean tempera- 

 tures of the stations, which was 9| a. m., I have concluded that the 

 difference between the real hourly mean temperatures of both days 

 would be greater after that hour, in the hot part, than before it in 

 in the cold part of the day. Guided by this supposition it might be 

 expected that the real mean temperature of the hours 8, 9 and 10 

 on the 3rd, would differ comparatively little from those at the same 

 hours on the 1st. 



This was made still more probable, from the small range of the 

 curves, which is less than half that of the curves of the stations. 



The temperature at 9 on the 3rd 26° .4 (Table V. Col. II.) agreeing 

 nearest, within the probable limits, with the temperature of the same 

 hour on the 1st, 26°. 7, I have taken it as the correct one. 



