Chase.] 



348 



[March. 



The nearest average temperatures are found in the third division, 

 as is shown below. 



Average of temperature at 2h., 8h., 14h., and 20h., and of the en- 

 tire day. 



The following table presents all the co-ordinate positive values of 

 S., R., and B., that can be obtained from the Girard College and 

 St. Helena means. 



The percentages of the calculated values correspond very nearly 

 with the means of the earliest Girard College and St. Helena values. 



It may be inferred from this comparison, that the rotation element 

 of daily heat is least affected, and the solar element most affected 

 by extraneous causes, (of which moisture is probably the chief); 

 that the first division gives the best, and the third division the 

 poorest results ; that the proportion of thermometric variation which 

 is attributable to rotation is between .4 and .5 of the average total 

 daily variation, and that the most difficult element to determine 

 satisfactorily is S., which is modified by many local disturbing influ- 



