The beginner, the practical worker, the student and the engineer, will find in this book a great amount of information regarding gas-torch and Thermit welding practice and equip ment. No toil or expense has been spared to gather material of real and lasting value. Shops have been visited and data and photographs obtained first hand. Practically every book on welding has been carefully scrutinized for helpful suggestions. The services of experts have been engaged to give the results of long practice and research in their special lines. Each and every plan known to the experienced editor has been employed to give the reader the highest possible grade of information. The historical references have been cut to the barest state ment of facts as we have been able to obtain them, yet they are ample enough to give the inquiring mind the genesis of each class. Foreign methods and equipment have not been touched upon, except in a few instances, because such treatment would add too greatly to the bulk of this work, without adding an appreciable amount to its real value, since the methods and standard equipment here are, in general, far in advance of anything similar elsewhere.