With such encouragement and example the scheme of watch-making was commenced. Soon large factories were built, and by the time of the Centennial Exhibition in 1876, the American Watch Company of Waltham, Massachusetts, were enabled to present an exhibit of watch movements made by machinery, which astonished the world. Other great companies in different parts of the country soon followed with the same general system. Machines, working with the apparent intelligence and facility of human minds and hands, and with greater mathematical accuracy than was possible with the hands, appeared:--for cutting out the finest teeth from blank wheels stamped out from steel or brass; for making and cutting the smallest, finest threaded screws by the thousands per hour and with greatest uniformity and accuracy; for jewel-making; for cutting and polishing by diamonds, or sapphire-armed tools, the rough, unpolished diamond and ruby, crysolite, garnet, or aqua-marine, and for boring, finishing and setting the same; for the formation of the most delicate pins or arbors; for the making of the escapements, including forks, pallets, rollers, and scape wheels; for making springs and balances, including the main-springs and hair-springs; for making and setting the stem-winding parts; for making the cases, and engraving the same, etc. The list would be too long to simply name all the ingenious machines there exhibited and subsequently invented for every important operation. It was the aim of these manufacturers to locate every great factory in some quiet and attractive spot, free from the dust of town, and city, and divide it into many departments, from the blacksmithing to the packing and transportation of the completed article; and to conduct every department with the best mechanical and mathematical skill that money and brains could provide. The same system was followed with equal success in producing the first-class pocket-chronometer for the nicest work to which chronometers can be put. Thus with every watch and its every part made the exact duplicate of its fellow, uniformity in time-keeping has been established; and the simile of Pope is no longer so correct, “’Tis with our judgments as our watches, none go just alike, yet each believes his own.” A simple statement of this system illustrates with greater force than an entire volume the revolution the nineteenth century has produced in the useful art of horology. And yet the story should not omit reference to the application of the electric system to clocks, whereby clocks at distant points of a city or country are connected, automatically corrected and set to standard time from a central observatory or other time station.