Notices of Books . 
263 
1878.J 
England, and the formation of dew is described. The account 
of liquid water is followed by that of solid water (Chap. IV.), 
and the principal physical properties of ice and snow receive full 
attention. A chapter on evaporation shows the connection be- 
tween it and the rainfall. 
The sixth chapter is devoted to the atmosphere, the chemical 
nature of which is fully discussed. This is followed by an ac- 
count of its physical properties, and of the perturbations which 
arise owing to alterations in the pressure. “ The Times ” 
weather-chart is reproduced and described ; also the barometer- 
charts of the “ Standard ” and “ Daily Telegraph.” The 
chemical and physical history of the air is followed by a chapter 
in which the composition of pure water is demonstrated. The 
constituents of mineral waters and of sea-water are discussed, 
and analyses given. 
The ninth chapter is of a more geological character: it treats 
of the work of rain and rivers, the power of running water, and 
processes of denudation. The Thames is said, on the authority 
of Prof. Geikie, to discharge annually 1,865,903 cubic feet of 
sediment, to which must, of course, be added the mineral matter 
carried away in solution, which brings up the amount to 
14,000,000 cubic feet of solid matter. “ Imagine a huge die- 
shaped mass of stone 100 feet in length, 100 feet in width, and 
100 feet in height : this would contain one million cubic feet. 
No fewer, then, than fourteen of these gigantic cubes appear to 
be quietly stolen from the surface of the Thames basin by means 
of running water, and transported to the sea, in the course of a 
single year. But the Thames basin covers a very large area, 
and it will be found on calculation that, admitting the abstraction 
of this vast mass, the entire surface of the basin would be re- 
duced in level by only i-8ooth part of an inch every year. At 
the present rate of wear and tear, therefore, denudation can have 
lowered the surface of the Thames basin by hardly more than an 
inch since the Norman Conquest; and nearly a million years 
must elapse before the whole basin of the Thames will be worn 
down to the sea-level.” Prof. Geikie has calculated that, at the 
present rate of denudation, it would require 5^- million years to 
reduce the British Islands to a level with the surface of the sea. 
The tenth chapter is devoted to “ Ice and its Work:” — the 
mechanical expanding work of water in the aCt of freezing, the 
motions of glaciers, and so on. A capital engraving of the gla- 
cier of Zermatt is given on page 156. It is shown that the 
passage of a glacier across a country produces peculiarities which 
are not caused by any other process of denudation, and it is thus 
possible to infer with certainty that ice has been at work in a 
district in which ice is now never seen. The flat-domed hillocks 
known as roches montonnees are thus produced, and they may be 
detedfed in Ireland, Cumberland, Scotland, and North Wales, 
together with bloce perches , and vestiges of old moraines. 
