246 Transactions of the South African Philosophical Soctety. 
of the two places are just such as would be expected from the contrast 
of continental and coast stations: the mean daily temperature 
ranging from 44°6 (July 17th) to 80°:2 (Dec. 28th) at Kimberley ; 
and from 62°-0 (July 17th) to 79°°2 (Jan. 27th) at Durban—or rather 
less than one-half the other. The respective ranges from the lowest 
mean daily minimum to the highest mean daily maximum are— 
At Kimberley from 32°:1 (July 17th) to 98°-4 (Dec. 28th), 
At Durban from 51°-7 (July 18th) to 90°°4 (Jan. 27th). 
For the extreme range of temperature observed in the whole ten 
years, we have: at Kimberley 20°:0 to 108°-5—the latter occurring in 
the midst of what would appear to be an annual wave of high 
maximum temperature at the end of January—and at Durban 42°'3 to 
110°:6, the latter in a hot wind of the spring months. 
By suitably choosing the scales on the paper it will be easily seen 
that the maximum temperature curve for Kimberley is almost 
identically the same as the mean pressure curves, inverted, for both 
Kimberley and Durban, either, as it happens, following closely upon 
the sun’s changes of declination. An approximate formula for the 
relationship in inches and degrees Fahr., is— 
100p +t=0 
where p is the total increase of pressure and ¢ the total increase of 
temperature reckoned from any epoch. 
The Durban temperatures lag very considerably behind those of 
Kimberley, in the summer months at any rate, and have no simple 
relationship to the collateral pressures. This is doubtless brought 
about by the vicinity of the ocean, and to a smaller extent by the 
greater quantity of vegetation, the moisture of the air along the Natal 
coast, and by the greater cloudiness of the sky. Clouds, generally 
speaking, prevent loss of temperature during the night in proportion 
to the area of blue sky hidden, and up to acertain limit—which does 
not, apparently, differ greatly at Kimberley from 50 per cent. of sky 
obscured—assist the rise of temperature during the day. Below this 
limit they admit more direct heat from the sun than they allow to 
radiate from the earth, but in a less and less degree as the sky is less 
cloudy ; above it the quantity of heat admitted bears a less and less 
proportion to the amount checked in its radiation. Moreover, apart 
from the influence of the clouds, 7.e., the humidity of the upper air, 
the influence due to the amount of moisture, or rather the humidity, 
of the lower air is greater than one would expect at first, although 
Tyndall’s “fairy tales,’’ as Prof. Callendar calls them, would not 
