1'KKFACF TO FIFTH EDITION. The iiivt edition of this work, which, can, in its present form, be justly called a practical compilation of original research, \vas issued sooner than it would, have been, had not the author been anxious to combat and thwart impractical theories and practices that some inexperienced in general founding" were laboring1 to establish, and which can be found in past records of trade papers and engineering" societies, etc., and are now proven to be incorrect. The original information and reforms advanced in this work were too far in advance of the times to escape, severe criticism or insure tlu: popular support they were, entitled t<>, but are now rrrriving in such measure as to be very gratifying to the author. The impra.ct.ical theories and practices that were advanced arc not yet all set, aside or acknowledged to be wrong and injurious as they should be by their advocates. However, the exhaustion of the third and fourth editions of this work in the short period of two months is a strong endorsement of the original practices, reforms* etc., advanced, and its practical utility. Time will demonstrate to all those not yet convinced of the impracticability of past teaching's what is correct. XoJ only docs the larger sale of this work demonstrate its growing popularity, but also forcibly illustrates the advancement of founders to accept its seen on the next two pages from a few of many testimonials tendered him during the year 1901.