. became of different colors, those in the rear being a ^ < ■ I » ■ This invention has been patented by Mr. Adam H. IMPROVED CAISSON. vivid green, changing to purple, while the foremost Bell, of Hillsborough, 111. The object of the invention shown in the annexed and largest was a brilliant red. No… … by momentarily raising the temperature to a particu- McGOVERN'S IMPROVED CAISSON. lar degree, can also be acquired by subjecting the steel for a longer time to a much lower temperature. For borough. 111.,—is to facilitate the work of sinking coal example, the temper which the annealing color—yellow…
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