12 
contribute to the increase of social wealth the elements of production 
previously unknown. Thus are we led to receive with interest works 
which can throw a new light on the condition of regions which may 
have been known for a long time, and which make known the conditions 
of their prosperity. It is under this title that the work of the Rev. J. C. 
Brown on the Hydrology of South Africa appears deserving of notice ; 
but it is so also from other points of view. Mr Brown, after a previous 
residence in the colony of the Cape, whither he had been sent in 1844 
as a missionary and head of a religious congregation, returned thither 
in 1863 as Professor of Botany in the College of South Africa, and he 
remained there some years. In both of these positions he had occasion to 
travel through the colony in all directions, and had opportunities to col- 
lect most valuable information in regard to its physical geography. Mr 
Brown on going out to the Cape knew nothing of the works which had 
for their object to determine the influence of forests on the climate, on 
the quantity of rain, and on the river-courses in Europe ; he had never 
heard mention of the work of M. Surell on the torrents of the Alps, or 
of that of M. Mathieu on forest meteorology, nor of those of M. 
Domontzey, Costa de Bastelica, and so many others on the subject of 
réboisement ; and yet in studying by himself, and without bias, the 
climatic condition of South Africa, he came to perceive that the dis- 
turbances in the regularity of the flow of rivers within the historic 
period should be attributed in a large measure to the destruction of 
forests ; and he meets in agreement on this- point the savants whose 
names have been mentioned. We have thougnt it might not be with- 
out interest to readers of the Revue to l:ave in the lines of Mr Brown a 
collection of phenomena which, in their manifestation at any speci- 
fied point are not less due to general causes, the effects of which 
may be to make themselves felt everywhere where there may be 
existent the same conditions than to aught else.’ And there follows a 
lengthened article in illustration. 
X.—Water Supply of South Africa, and Facilities for 
the Storage of it. Price 18s 6d. 
In this volume are detailed meteorological observations 
on the humidity of the air and the rainfall, on clouds, and 
winds, and thunder-storms; sources from which is derived 
the supply of moisture which is at present ‘available for 
agricultural operations in the Colony of the Cape of Good 
Hope and regions beyond, embracing the atmosphere, the 
rainfall, rivers, fountains, subterranean streams and reser- 
voirs, and the sea; and the supply of water and facilities 
for the storage of it in each of the divisions of the colony 
