Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. The authors believe that they have succeeded here, as in their earlier book in this field, in eliminating nonessentials, in emphasizing the great principles, and in presenting the matter in a new but perfectly natural form, with definite and valuable applications which initiate the student into the actual work of the shop. They hope that their efforts will meet with the approval of teachers and students alike.