Notwithstanding foreign competition, possibly because of that stimulus, improvements were constantly being made in methods and machinery. The agitator now used on paper machines, consisting of a semi-cylindrical cradle vibrating so as to prevent the fibers from being arranged parallel one to another, the result of which would be to make the paper weaker in one direction than in the other, was patented by Reuben Fairchild of Trumbull, Connecticut, in 1829. In the following year Thomas Gilpin of Philadelphia invented what are called “calenders,” for giving the polished surface to paper. These are described later, in Chapter V. True cylinders were first made in this same year by an inventor in England. The result was gained by grinding the rollers together while a stream of water flowed over them, this operation requiring many weeks. Through these various inventions and improvements, and through the introduction of machinery from Europe, by means of which the coarsest of rags and other materials were cleaned, bleached, and purified, and increased three hundred per cent in value, a decided impetus was imparted to the manufacture. ♦Improved machinery♦ The advance in the industry during the following years was so marked that in 1842, according to an estimate made at a meeting of paper-makers held in New York City in that year, the paper-mill property of the United States was valued at $16,000,000, and the annual output at $15,000,000, while the value of rags imported from Europe amounted to $468,230, and the raw stock, rags, and other material collected in the United States to $6,000,000. With the adoption, in 1843, of the devices for a rotating strainer, for draining water from the pulp in the washing or beating vats, came another advance in the process of paper-making. ♦The first paper-house in Chicago♦