of which I have made extensive use, but also for kindly allowing me the use of their proof sheets of the issue for 1915, and for permitting me to reproduce several valuable illustrations. I wish also to thank the Powell Duffryn Steam Coal Co. and the Ashington Coal Co. for kindly providing me with several photographs.
The first impression of this book having been exhausted, a second is being printed from moulds of the original edition. The opportunity has been taken to make a few verbal corrections of errors which somehow crept into the original manuscript. It has seemed better thus to limit the changes, rather than to attempt any revision of the book so as to make a new edition. The time for this is not appropriate because the coal mining industry and coal trade of this country are in an extraordinary state of flux, and any description of present conditions would very soon be out of date.
The interference of the War with the normal condition and expansion of the coal trade is indicated, however, by some of the principal statistics for recent years which I have collected and printed in a new Appendix to this book. (See page 864). It will be seen that the output for the United Kingdom began to decline in 1914, went still lower in 1915, recovered a little in 1916, and since then has continually decreased. Some three or four different causes have
