Number 53 in a long series of volumes used for early 20th C correspondence courses. Preface says "The information. . . can be immediately applied in practice, so that the student may be enabled to exchange his present vocation for a more congenial one, or to rise to a higher level in the one he now pursues." The information is arranged in a naturally consecutive order, so that the fundamental principles underlying the advanced subjects may bwe thoroughly understood before the broader and freer subjects. Most of the subjects are covered in approximately 75 pages, with numerous illustration.