Some Besults from the Periodic Formul(B. 117 



two days later than it does at Aliwal North. Also a^ displays a 

 tendency to be greater or less according as A^ is greater or less. 

 It seems not unlikely that the values of a^ may depend in some 

 measure upon the geographical gradients. 



The ratio of a^ [max.] to a^] [min.] is one of lesser inequality at 

 Durban and of greater inequality at Kimberley, approaching equality 

 at something over 250 miles from the sea. Also the ratio of 

 «2 [max.] to ^2 [min.] increases in magnitude from the sea to the 

 interior. The values of these ratios are : — 



Durban -73 -36 



Umtata -43 -35 



Queenstown -88 -62 



Aliwal North -83 -70 



Philippolis -95 -90 



Kimberley 1-21 -95 



They intimate that the influence of the ocean upon the tempera- 

 tures is appreciable up to at least 250 miles inland. But not 

 because of any increase of moisture in the air consequent upon 

 nearer approach to the sea ; for, as it happens, there is not, so far 

 as can be judged from the observations, any very great increase in 

 this element between Kimberley and Queenstown. We judge from 

 the values of a^ and a^, Aj and Ag, for Umtata, that the character 

 of its annual curve of day temperature is oceanic, whereas that of 

 the night is continental ; so that we find, upon reference to the 

 records, that the analytical constants translate themselves into a 

 mean daily range of temperature more than half as great again 

 in the winter than it is in the summer. Now at Kimberley we 

 get the greatest range of temperature in the late spring months, 

 and the fact has a partial explanation in the excessive dryness of 

 the air then. But at Umtata the percentage of humidity seems not to 

 vary very much month by month during the year, and thus furnishes 

 no key to the interpretation of a daily range of temperature equal, 

 at its maximum in the winter, to the greatest found on the Northern 

 Karoo, and at its minimum in the summer, scarcely greater than 

 that of Durban. 



It seems to be a reasonable conclusion, from the analysis, that we 

 have really before us a phenomenon analogous to, if not identical 

 with, the familiar land-and-sea breeze, whereby the littoral air is 

 displaced seawards during the night and landwards during the day, 

 carrying its temperature with it. Probably the bodily transfer of 

 air to and fro may be considerable, preponderating considerably 



