544 
Notices of Boohs, 
[Odlober, 
In successive chapters the author considers the straining adtion 
to which machines are subjedt ; the strength of materials, fasten- 
ings, pipes, and cylinders ; of pivots, axles, and shafting ; of 
bearings for rotating-pieces ; of toothed, belt, and rope gearing ; 
of link-work ; and of pistons, valves, and cocks. 
The work may be fairly pronounced to have no small share of 
the invaluable attribute of thoroughness, and we think that it is 
very well calculated to effedt its primary objedt. This, as the 
author tells us, is “ to explain the principles that are available as 
guides in machine-construdfion. So far as it succeeds in this it 
will place the draughtsman in the best position to make use of 
the fadts which come under his notice in the workshops.” We 
must call particular attention to these last few words, because 
they seem to us to summarise the whole purpose of technical 
education. Every artizan ought to be so trained that he may 
make use of such fadts. To this end he must be taught to 
observe, in order that the fadts may not altogether escape him, 
and he must be acquainted with the scientific principles on which 
his art is based, in order that he may know how to deal with 
such fadts. 
The Ancient Life-History of the Earth, a Comprehensive Outline 
of the Principles and Leading Facts of P alee ontological 
Science. By H. Alleyne Nicholson, M.D., D.Sc. Edin- 
burgh and London : Blackwood and Sons. 
The especial objedt of the work before us, as we are told in the 
Preface, is the study of fossil animals from the historical point 
of view, regarding them “ principally as so many landmarks in 
the ancient records of the world,” and examining “ their relations 
to the chronological succession of the strata in which they are 
entombed.” Their morphology and their relation to existing forms 
of life occupy here a mere subordinate place. 
This preliminary demarcation of his subjedt having been 
drawn, the author enters upon the consideration of the laws of 
geological adtion. Happily observing that, in its stridl sense, 
“ Geology is nothing more than the Physical Geography of the 
past, just as Physical Geography is the Geology of to-day,” he 
discusses, in a most philosophical spirit, the two grand conflicting 
theories of Catastrophism and Uniformitarianism. Here, whilst 
insisting that the present state of our earth is “ really the result 
of the tranquil and regulated adtion of known forces through un- 
numbered and innumerable centuries,” — that “ the history of the 
earth has been one of law in all past time, as it is now,” — that 
the successive groups of animals and plants revealed to us in 
turning over the pages of the “ stone book ” are, “ to a greater 
or less extent, diredtly connected with one another, each being 
