10 Transactions of the South African Philosophical Society. 
Previously to September 18th neither of the experimental patches 
had emerged from the morning shadow cast by some adjacent gum- 
trees at vii. From that time until the end of the month the red 
patch was either in partial shadow or full sunshine at vili., while the 
blue was in shadow or partial shadow at the same time. For this 
reason the vii. observations after that date are not to be taken in the 
comparisons, the rest of the observations being nevertheless quite 
trustworthy. 
The general conclusions to be drawn from Table I. are :— 
1. The air is always warmer above the surface of the blue-ground 
than it is above the red sand. 
2. Beneath the surface the blue-ground is always warmer by night 
and cooler by day than the red sand. 
3. Finally, blue-ground is the better reflector and therefore the 
worse absorber: heat passes less readily, in or out, across the 
bounding surfaces of its particles. The uniformly greater tempe- 
rature of the air just above its surface is a reflection effect by day, 
and an effect of actual warming by contact and conduction during 
the night. 
The soil of many of the gardens in and about Kimberley is little 
besides blue-ground taken from the waste material of the heaps of 
tailings. That they should often be so flourishing may be partly 
due to the more equable thermal properties of blue-ground. Of 
humus they have obviously not a trace to begin with. Fruit-trees 
generally blossom much earlier in the spring in Kimberley, which is 
built almost entirely on débris from the mines, than they do in Kenil- 
worth, where there is not any of this material; and a certain succulent 
plant known locally as the wild tobacco develops more luxuriantly 
upon the tailing-heaps than it ever does upon the native sand. A 
mixture of red sand and blue-ground seems also to make a good soil 
for a garden. 
Liffects on Climate. 
The great differences in the thermal properties of blue-ground and 
encroaching very little into the spaces which should be left blank by clouds. 
It follows as a necessary consequence that the maximum amount of sunshine 
in the diurnal range is displaced too near to noon by the Campbell-Stokes 
instrument. 
Clouds being relatively rare at Kimberley, it is doubtful if a Campbell-Stokes 
recorder of the very best construction could record more sunshine than the 
Jordan instrument. And here it may not be out of place to add that Kimberley 
is perhaps one of the most sunny places in the world. The mean sunshine for 
the year is about 76 per cent. of the greatest amount possible, Allahabad (India) 
having perhaps 70 per cent., Cordoba (S. America) 62 per cent., Adelaide (S. 
Australia) 60 per cent., and St. Aubin’s (Jersey) 39 per cent. 
