There is only space for a passing mention of the immense amount of data which Edison gathered, tabulated, and charted in his study and evolution of strategical plans suggested by him to the government in the line of lessening the destruction by submarines. He spent day and night for several months with a number of assistants working out these plans. It is not possible to make more specific mention of them here, as they are too voluminous for these pages. With this tremendous amount of work pressing on him he retained his accustomed good health and buoyancy, due, undoubtedly, to his cheerful spirit, philosophical nature, and abstemious living. Soon after the armistice was signed his experimental work for the government came to an end, and he then switched back to the general supervision of his business interests and to his ceaseless experiments through which he is continually making improvements and refinements in the products of the large industries which he established and in which he is so greatly interested. Mention should also be made of another extensive project he has undertaken, and that is the production of rubber from plants, weeds, bushes, shrubs, etc., grown in the United States. This he speaks of as "emergency" rubber, to be resorted to in case our country should ever be embarrassed in obtaining a supply of rubber from present sources. This is a tremendous problem, but he is applying to its solution the same resourceful powers that have characterized his previous endeavors. Herein, and in the development of new ideas, lies Edison's daily work and pleasure, and although he is in his eighties at this writing, with still boundless energy, it may be said of him "Age cannot wither him, nor custom stale His infinite variety." End of Project Gutenberg's The boys' life of Edison, by William Meadowcroft