238 Scientific Intelligence . 



It may be proper to accompany the preceding Summary with a few 

 remarks. 



1. To determine the average or mean temperature of the atmos- 

 phere, at any given place, is a leading problem in Meteorology. For 

 the solution of this problem various methods have been proposed ; but 

 among these none seems more simple and convenient than that pro- 

 posed by the author of the article Meteorology, in the Edinburgh 

 Enclopsedia ; namely, to take the average of the temperatures at 10 

 o'clock, morning and evening, for the mean temperature of the day. 

 The fact of the mean of the temperatures at these two hours, corre- 

 sponding very nearly with the daily mean, has been ascertained and 

 confirmed by accurate observation. To render the observations, made 

 during the past year, at this place, subservient to the purpose of de- 

 termining the mean temperature, I accordingly adopted this prin- 

 ciple, recommended both by simplicity, and by the accuracy of the re- 

 sults to which it leads, and noted regularly, the height of the ther- 

 mometer at 10 A.M. and at 10 P.M. The third column in the pre- 

 ceding tabular summary exhibits the mean for each month ; and the 

 average of these means gives 45°*2, for the mean temperature for the 

 year. 



In order to have a check upon the result, I examined about the 

 middle of each month, the temperature of a copious well shaded 

 spring issuing from the northern side of a hill. The thermometer 

 employed for this purpose, I find to s-.tand about three-fourths of a 

 degree higher than the thermometer with which the temperature of 

 the atmosphere is observed. In the monthly report no allowance 

 was made for this difference ; but this has been done in the preceding 

 summary ; and the average temperature of spring water for the year 

 is found to be 45 0, 2 ; a result corresponding precisely with that ob- 

 tained for the mean temperature of the atmosphere. 



2. As the relative humidity of the atmosphere depends in no small 

 degree on temperature, it may reasonably be concluded, that since 

 the mean temperature, at 10 o'clock morning and 'evening, does not 

 differ materially from the mean temperature for the whole day, the 

 average of the hygrometer at these hours will be an approximation 

 to the mean of the day. It is on this principle that I have registered 

 the hygrometer at 10 A.M. and 10 P.M., and have recorded the 

 results thus obtained as the means for the several months. Taking 

 the average for the whole year, we obtain for the mean height of 

 Leslie's hygrometer, at this place, about 12°. 



3. With regard to the barometer, I am not aware of any principle 

 that should lead to the choice of any other hours of observation, than 

 those adopted for the thermometer and hygrometer. I have, accord- 

 ingly, noted the height of the barometer also, at 10 A.M. and 10 

 P.M., and considered the mean of these observations as the mean for 

 the whole day. The mean thus obtained for the whole year is 

 29-309 inches. 



4. It seems to be worth while to compare this last result with the 

 mean height of the barometer on the sea shore, and to determine 

 thence the height of the place of observations. Now, according to 

 the most accurate observations, the average height of the barometer 

 for our climate, at the level of the sea, appears to be 29-830 inches. 



