IN general, the writing of works such as that which the author herewith presents, is accompanied by several features the effect of which is to materially lessen the excellent results which such a work should produce.

One of the errors to which we allude, is the tendency of the author on trade subjects to write in too technical a manner, that is, to handle his subject in such a manner that none but the most educated of his readers are able to thoroughly grasp the principles presented.

For instance, since the plumber is seldom to be found who can handle an algebraic equation, it would certainly seem far better to present a necessary principle by means of arithmetic rather than by means of algebra, and if there is no other way than by means of algebra the author should see to it that he fully explains the entire operation at length, in such a manner that the reader who has not had the advantage of instruction in such branches may be able to grasp the subject. In other words, the author should stand in the same position to his readers that the teacher does to his pupils. It is his duty to honestly instruct, and not merely to fill his pages with facts which, though valuable, are presented in such a manner as not to be easily understood by the average reader.

A second serious though unintentional error on the part of many authors is the omission of minor details. While to the author, who is naturally a man of experience and education in his special line of work, the statement of simple, and to him obvious, facts seems a matter of foolishness, ofttimes, to many of his younger and more inexperienced readers, the statement of these simple things is a matter of utmost importance, and a means of establishing the main principle more strongly in their minds.

The author of this work frankly confesses to surprise at the absence of knowledge of rudiments which he knows from long experience to exist, and, knowing that this condition does exist, has no apology to offer for the statement of various facts in his writings which certainly should be known and understood. Indeed, it is his firm belief that one of the chief factors in obtaining whatever success has come to him in his line of work, is the fact that he has never hesitated to give the minor details and to state simple facts. Certainly if these are not thoroughly understood, the main subject under consideration cannot possibly be digested as thoroughly as it should be.

A third defect that often creeps into trade text books is the lack of systematic treatment of the various subjects considered.

A book so written cannot give to the reader as clear an understanding as a work which takes up the various subjects in proper order. By this we do not mean to infer that there is only one order that may be properly followed, but merely to emphasize the fact that the mere statement of facts is not sufficient. There must be a proper order.

Knowing the tendency toward these errors the author has honestly endeavored to avoid them, and to give his readers such information as will be of practical use to them.

The Author. November, 1910.