Pressure and Temperature Results for the Great Plateau. 271 
periodic phenomena we have the very interesting, deep, W-shaped 
depression covering the whole country from May 11-29, already 
spoken of; and the period of abnormal pressure from about 
September 25th to October 17th, felt at the coast, only, as an 
increase, but on the table-land as a slackening of pressure, and 
due doubtless to the overflow of heated and expanded air from 
inland coastwards when the transfer along the parallels is tem- 
porarily greater than the seasonal meridional drift to the other 
hemisphere. 
It is significant that the occasional abnormal hot winds of Durban 
blow at the season when the air is thus supposed to expand out- 
wards from the table-land. They exercise a striking disturbing 
influence upon the regularity of the curve of maximum tempera- 
tures (fig. 1) between August and December. The Government 
astronomer for Natal thus describes some that visited Durban in 
the early summer of 1896 :— 
“Among the meteorological phenomena of the year calling for 
notice was the exceedingly high temperature registered on Sep- 
tember 21st and October 3rd. 
“September 21st was the hottest day recorded at the Observatory, 
and probably the hottest day experienced in Durban during the 
last twenty years.. The early morning was cool, but shortly after 
8 a.m. the wind shifted towards the N.W., and the temperature 
began to rise fast, the wind growing hotter and hotter, and the 
barometer fell slowly. By nine o’clock the temperature had risen 
from 68° to 85°, and by half-past ten o’clock it had risen to over 
100°. Then the wind shifted back towards the N.E., and under the 
influence of the sea-breeze the temperature fell fast, until by eleven 
o'clock it was only a little above 90°. Then the wind went back to 
the N.W. and grew stronger, coming in sharp gusts, with the effect 
of sending the temperature up fast, until by noon it had reached 
108°. By two o’clock the temperature reached its maximum, the 
thermometer then registering 109°°6, and it was still over 100° 
at three o’clock, not falling below 100° until after 4 p.m., after 
having been above 100° for over six hours. During the night the 
temperature fell steadily to 63°, the change of. temperature in twelve 
hours, therefore, being over 48°. 
‘At the Observatory we have no record of so hot a day. It is 
true that once, previously, we have registered a higher tempera- 
ture, and, curiously enough, that was on exactly the same date 
in the year 1890. Then the maximum temperature registered was 
110°°6, or exactly a degree greater; but the intense heat was of far 
shorter duration, the temperature being only 70° at 6 a.m., and had 
18 
