Some of the earliest mechanical measuring tools were used in mechanical manufacturing, such as the square, calipers, etc. In the 16th century, smooth gauges began to be used in gun manufacture. In 1772 and 1805, The British J. Watt and H. Modsley have made the use of thread pair principle to measure the length of the watt micrometer and calibration with the measuring long machine. Since the middle of the 19th century, there have been similar to the modern mechanical outside micrometer and vernier caliper measuring tools. In the late 19th century, sets of measuring blocks appeared. Following mechanical measuring tools came a batch of optical measuring tools. At the end of the 19th century, vertical length measuring instrument appeared, at the beginning of the 20th century, the length measuring machine appeared. By the 1920s, it had been used in mechanical manufacturing projectors, tool microscopes, optical micrometers and other measurements. In 1928, the gas-momentum meter appeared. It is a measurement tool suitable for mass production. Electrical measuring tools came into being in the 1930s. The first ones were boundary gauges and profilers made of inductive length sensors. In the late 1950s, coordinate measuring machines appeared with digital display of measurement results. In the mid-1960s, coordinate measuring machines with computer-aided measurements were used in mechanical manufacturing. At the beginning of the 1970s, the computer digital control of the gear meter, so far, the measurement tools into the application of electronic computers stage.