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TEANSVAAL SEA-LEVEL TEMPEEATURES. 
By E. T. a. Innes. 
(Eead April 6, 1908.) 
(Plates X.-XIL) 
The reduction of plateau temperatures to sea-level temperatures is 
a problem that does not admit a definite solution. On land-surfaces both 
insolation and radiation are more active than on water-surfaces, so that 
the variation of temperature on the former is much larger. The endeavour 
of the present paper is to present figures showing the reduction of 
Transvaal High Veld temperatures to sea-level. The figures are based 
on two years' means of shade temperatures published by the Transvaal 
Meteorological Department in its Annual Eeports for 1904-05 and 
1905-06. The results are independent of any hypothesis. The problem 
was presented thus : What reductions applied to the Transvaal tempera- 
tures will in the mean for the whole country reproduce the assumed 
temperatures at sea-level ? The sea-level temperatures assumed are 
based on Buchan's results, as published in Bartholomew's " Meteoro- 
logical Atlas." 
On squared paper, with the y axis for altitudes and the x axis for 
temperatures, points were places for the actual temperatures recorded at 
the dilferent altitudes, viz., sea-level and from 460 feet to 6,300 feet, but 
there were only a few points for places lower than 3,000 feet, or higher 
than 5,700 feet. A curve drawn through these points to the point at sea- 
level approximated closely enough to a parabolic form ; from this curve 
the reductions to sea-level were taken. 
If it should appear that the sea-level assumption must be corrected by 
a certain number of degrees, it will be sufficient to apply the same correc- 
tion to the Transvaal sea-level reductions. At the same time I do not 
consider that the tables given are final : they must be considered as a first 
approximation. Two years' means are an insecure foundation, and more 
work is wanted between the Transvaal and the sea-coast so as to fix the 
reduction to sea-level for intermediate heights. But it is claimed that as 
a first approximation the table and maps which are given will be found 
