562 



H. MOHN. METEOROLOGY. 



[noRW. POL. EXP. 



representing the month, reckoned from the middle of January. The first part 

 of the following Table shows the result of the computation of the annual 

 period for the depths 0-4, 08, 1-2, I'G and 20 metres. 



The second part of the Table gives the annual period for the surface, 

 for the depth of 3 metres, and for the air. The numbers used for the com- 

 pulation for these depths are those of the first part of the Table, introduced 

 in the formula 



log th = log to — f.h. 

 and computed by the method of least squares. 



The annual period for the air is computed from the means in the Table 

 on pp. 560, 561. 



M. E. is the mean difference: observed — calculated. 



The numbers in the above Table are represented graphically by the 

 diagrams on PI. X, (1) the annual period at the different depths and of the 

 air, (2) the vertical course of the temperature in each month, negative tempera- 



