PEEFACE vii 



than others which have been carried out abroad. Many 

 works of reference, periodicals and other sources have been 

 consulted. Particular informations are acknowledged in 

 their places ; but the author desires to express his indebted- 

 ness to many other writers particularly Dr. Fream, Mr. 

 J. E. Warington and Mr. A. D. Hall for much that cannot 

 be specifically mentioned. 



Several of the illustrations in the biological section were 

 supplied by Mr. John Golding of the Midland Agricultural 

 College, and some of the others are due to the courtesy of 

 various commercial firms. Thanks are due also to the 

 editor of the Journal of Gas Lighting, the secretary of 

 the Iron and Steel Institute, Mons. Eoussel of the Institut 

 Pasteur, and Mr. W. A. Cox of Albert's, for kind assistance 

 in this connection. 



J. M. 



CROSBY, 



1909. 



