every Hour of the Day at Leith Fort in 1824 and 1825. 371 



HAVING given, in the preceding Tables, all the numerical re- 

 sults of the hourly Register for 1824 and 1825, I shall now 

 proceed to consider some of the most important conclusions 

 which may be deduced from them. These relate, 



1. To the form and character of the annual and monthly 



daily curve, or the daily progression of temperature. 



2. To the determination of the two times of the day when 



the mean temperature occurs. 



3. To the relation between the mean temperature of the 24 



hours, and that of any single hour, or pair of similar 

 hours, &c. 



4. To the average daily range for each month. 



5. To the Parabolic form of the branches of the Annual Daily 



/ 



, oni 



1. On the Form and Character of the Annual and Monthly Daily 

 Curve, or the Daily Progression of Temperature. 



The daily curve for 1824 is projected in Plate XIV., from 

 the numbers in the last column of Table II., and forms the low- 

 est curve. The point of the curve for each of the 24 hours is 

 the mean of 366 observations. The temperature is lowest be- 

 tween 4 and 5 o'clock in the morning ; it then increases with 

 great regularity till three o'clock in the afternoon, when it de- 

 scends till it reaches its minimum at 5 o'clock in the morning. 

 The period during which it performs its ascending motion is 

 9 h 40', and the period of its descending motion is 14 h 20' ; the 

 heat of the day, therefore, advances with more rapidity than the 

 cold of the night. 



The daily curve of 1825 is projected in a similar manner in 

 Plate XIV. from the first column of Table IV., and forms the 



