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 the old building was repaired with this apparatus. The Field Museum never used the cement gun any more but some friends came along and offered to put money enough behind the idea to perfect, manufacture, and sell it. As with all such things the first money went and then a second like amount, but in the end the cement gun succeeded, and during the war it, among other things, was used to make the concrete ships. This occupied most of my time between 1907 and 1909. In fact, I drove the first motorized cement gun down to the house of its chief financial backer on Long Island in 1909, and went back to New York to go again to Africa.

As I am no longer financially interested in the cement gun, I may say with pride that there are now approximately 1,250 machines in use, not only in the United States, but also in the principal foreign countries. In addition to the use for which it was originally designed, that of restoring masonry and concrete structures, many other important purposes are now served by this mechanism. In coal mines it is being used to keep slate roofs from falling and to fireproof the timbers. Irrigation ditches and reservoirs are being lined and dams are being faced and protected against the destructive action of water and frost by this method. In tunnel construction, a lining put in with the cement gun prevents falls and insures an absolute sealing. It protects steel, protects piles against teredo and fire, protects structures against acid, restores boiler settings and preserves them from further action of the heat, rebuilds