PREFACE. 
THE Ten Lectures of which this volume is com- 
posed were delivered in the spring of 1878, in St. 
John's Wood, to a large audience of children and 
their friends, and at their conclusion I was asked by 
many of those present to publish them for a child's 
reading book. 
At first I hesitated, feeling that written words can 
never produce the same effect as viva-voce delivery. 
But the majority of my juvenile hearers were evidently 
so deeply interested that I am encouraged to think 
that the present work may - be a source of pleasure 
to a wider circle of young people, and at the same 
time awaken in them a love of nature and of the study 
of science. 
The Lectures were entirely rewritten from the 
short notes used when they were delivered. With 
the exception of the first of the series, none of them 
have any pretensions to originality, their object being 
merely to explain well-known natural facts in simple 
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