economics of military bridgework. Upon receiving an acquiescent reply, Major Lewis proceeded to the Capital, consulted Major General Beach, the Chief of Engineers, and made a like suggestion to him. The result was that the General agreed to write a "Foreword" for the chapter, and detailed Col. P. S. Bond, in consultation with some of his brother officers, to do the writing. The author deems the outcome an exceedingly valuable addition to his book; and he hopes that many of his readers, in consequence of its perusal, will be induced to take such an interest in military bridge engineering as to ensure that they shall be better prepared to serve our country in case of war than were most of the civilian engineers when the call to arms came in 1917.

It is intended that this shall be the last technical book which the author will ever write, for reasons explained in the concluding chapter; and he hopes that it and its immediate predecessor, "Bridge Engineering," will, for many a year to come, prove of real service to the engineers of his specialty, in the advancement of which, almost ever since graduation forty-five years ago, he has taken an intense and absorbing interest.