PREFACE 



I AM encouraged by the kind reception given to the first 

 selection of papers from my weekly contributions to 

 the 'Daily Telegraph' to publish a second series of 'Science 

 from an Easy Chair,' of like form and size. I have given 

 in this, as in the earlier volume, some figures in illustration 

 of the articles, and have, here and there, revised and 

 expanded the originals. It must be remembered that 

 these papers are, strictly speaking, " occasional." There is 

 no attempt to treat any subject in a complete or detailed 

 way. The chapters are purposely arranged so as to pro- 

 duce a variegated result — a mixed assortment in which 

 it is hoped that readers of differing interests may find 

 each something to his taste. I hope that some may be 

 led by the reading of one of my short chapters to look 

 further into the matter of which it treats and to consult 

 more thorough-going treatises abounding in details and 

 pictures which are beyond the scope of this little volume. 

 The two volumes bearing the title, ' Science from an 

 Easy Chair,' viz. the present one (second series) and 

 that published in 19 lO by Methuen & Co., contain only 



