map of the country over which the airplane has flown which is as accurate and far more detailed than a map drawn from surveys. This invention opens up an entirely new field for the use of airplanes and a possible revolution in former methods of mapping. The Engineers likewise produced portable machine, blacksmith, and lithographic shops, the capacity of the portable lithographic truck-sets furnished the 29th Engineers—the Surveying and Printing Regiment—being greater than that of the permanent map-reproduction plant of the Geological Survey in Washington. Mobile sterilizers, water-tanks, job-presses, photographic laboratories, derricks, pile-drivers, road-sprinklers, and oilers were all asked for by the A. E. F., whereupon the Engineers designed them and shipped them to France. I fully realize that what I have written in the preceding pages contains no mention of the supply work performed by the corps in the United States, which was so enormous that 27 per cent of all the tonnage shipped to France up to the signing of the Armistice was from or for the Engineers. Furthermore, I have touched only here and there upon the activities of the corps oversea, where in addition to the enormous amount of engineering work which had to be done with the armies, including fighting, the construction of fortifications, and the building of roads, railways, and bridges, it executed an incredible amount of general construction, such as docks and warehouses, railroad yards and railroad bridges, camps and hospitals, balloon sheds and airplane hangars, not to mention the installation of water, heating, lighting, and sanitary systems. And, bear in mind, the oversea activities of the Engineers were not confined to France, but extended to England, Italy, Russia, and Siberia. * * * * * “_Essayons!_” The more I have seen of the work of the Engineers, the more appropriate seems their motto. “_Essayons!_” There is apparently nothing that these men with the castles on their collars will not essay. And everything they essay they accomplish. III THE GAS-MAKERS Were you to grow up with a boy who eventually became widely talked about, watching him pass from knickerbockers to trousers and from youthful shyness to burly aggressiveness, the chances are that you would follow his career with an almost proprietary interest, and that when you came upon his picture in _The World’s Work_ or _The Police Gazette_, according to whether he had become famous or notorious, you would display it to your friends, explaining proudly: “Why, I’ve known him ever since he was a youngster. I always felt sure that he would attract attention some day.”