vl PREFACE TO THE FIRST EDITION 



who, with Httle definite scientific training, are 

 interested in the more important conclusions of 

 scientific thought. 



The writer has been fortunate in his surround- 

 ings, where the knowledge and insight of one 

 worker are placed freely and ungrudgingly at 

 the service of another in the day of his need. 

 In the present undertaking he records gratefully 

 the help of several friends who have read the 

 proof sheets of the parts dealing with subjects 

 with which their names are closely associated. 

 Mr F. H. Neville criticised the chapter on The 

 Philosophical Basis of Physical Science, and that 

 on Fusion and Solidification. Lord Berkeley 

 read the account of The Problems of Solution. 

 Professor J. J. Thomson saw the manuscript of 

 the original article on which is founded the 

 chapters on Conduction of Electricity through 

 Gases and Radio-Activity. Professor Larmor 

 revised the account of Atoms and ^ther, while 

 Mr H. F. Newall read the chapter on Astro- 

 Physics. For this assistance the writer expresses 

 his cordial gratitude. He wishes especially to 

 thank his wife for continual correction both of 

 the manuscript and of the proof sheets. 



The editor of the Quarterly Review has 

 kindly allowed use to be made of the article 

 on Matter and Electricity which appeared in 

 January 1904. Professor George E. Hale was 

 good enough to permit some of his photographs 

 of the sun to be reproduced, while, for other 

 illustrations, acknowledgments are due to the 

 Royal Society, to Mr Heycock and Mr Neville, 

 to Mr J. A. Ewing, and to Mr G. T. Beilby. 

 Lord Kelvin kindly sent a signed portrait, and 



