The development of the automobile was retarded for years, because, while iron shod horses, it would not successfully shoe automobile wheels. The greatest obstacle to the mechanical perfection, as well as to the development of the automobile by general adoption, were road shock to the automobile and mutilation by the automobile of the roads. The pneumatic tire removed both obstacles simultaneously. The pneumatic tire was invented by an Englishman named Thompson, who patented it in 1845. Dunlop, an Irishman, was the pioneer manufacturer in 1888, and Michelin of France first applied it to the automobile. The manufacture of body parts is obviously a tremendous industry, and while the body is a prime essential to the automobile, it was a part that existed in horse drawn vehicles, and, therefore, did not play the part that the pneumatic tire did in accelerating auto development. Comparable in importance to the tire was the nonskid chain, the invention of Parsons, an English engineer, who patented it in 1903. As the pneumatic tire enabled the automobile to be used more successfully and in larger numbers in good weather, so the nonskid chain enabled it to be used in bad weather. Prior to its adoption automobiles were used to only a limited extent in wet or slippery weather. Its adoption is credited with having added one month a year to the possible use of every automobile, a result which would naturally increase the number of automobiles used, through making them more efficient, and by decreasing the life of a car through added use. Next in importance in extending the field of purchasers of automobiles was the self-starter, the invention of Coleman, who, though little known to the public, is the inventor of so many things in electrical use as to be comparable to Edison. The electric self-starter is credited with creating a million automobile buyers, a large proportion of whom are women, and with having added nearly 15 per cent to the service of the motor car. Other aids to the successful commercialization of the automobile are solid tires, invented by Grant in 1896; the demountable rim, invented by Perlman in 1906; sliding transmission, the invention of Dyer; the nonskid tread, and chambered spark plugs, the latter invented by Canfield in 1898. Of minor improvements, of which there have been scores, the most notable were those of side doors, introduced by Marmon in 1902; tops to bodies, introduced in 1903; speedometer, gasoline pressure system, carburetor, shock absorber, electric lighting and oil gauge. The evolution of the automobile has been facilitated by every improvement which makes it easier of operation, and the sale of motor cars has been increased by them.