It is hardly too much to say that we owe to General Cullum more than to any other person the development in our service of systematic instruction in pontoniering. Before the Mexican War, Cullum and Halleck had ably argued the necessity of organizing engineer troops to be specially instructed as sappers, miners, and pontoniers. In an article on "Army Organization," in the "Democratic Review," were cited a striking series of instances in which bridge-trains or their lack had decided the issue of grand operations. The history of Napoleon's campaigns abounds in proofs of their necessity, and the testimony of the Great Captain was most emphatic on this point. His Placentia and Beresina crossings are specially instructive. The well-sustained argument of the article on "Army Organization" was a most effective aid to General Totten's efforts as Chief Engineer to secure the organization of our first engineer company. This company proved to be the well-timed and successful school in which our pontoon-drill grew up and became available for use in the present war. There are now four regular companies and several volunteer regiments of engineer troops, whose services are too highly valued to be hereafter ignored. In 1846, General Taylor reported, that, after the victories of Palo Alto and Resaca de la Palma, a pontoon-train would have enabled him to cross the Rio Grande "on the evening of the battle," take Matamoras "with all the artillery and stores of the enemy and a great number of prisoners,--in short, to destroy entirely the Mexican army." This striking evidence of the necessity of bridge-equipages as part of the material of army-trains coincided with the organization of the first engineer company, and led to the preparation of pontoon-trains for General Taylor and General Scott. General (then Captain) Cullum "had the almost exclusive supervision, devising, building, and preparing for service" of these trains, and of that used for instruction at West Point. To him is chiefly due the formation of the system of military bridges with India-rubber pontoons, which was most fully described and illustrated in the original memoir from which the volume now just published has grown. He subsequently, as Professor of Practical Engineering at the Military Academy, aided in developing and perfecting the pontoon-drill,--a department in which G.W. Smith, McClellan, and Duane ably and successfully labored.