Warren Marrison developed the first quartz clock in 1927. The running of a quartz clock is based on an electric property of the quartz crystal. When an electric field is applied to a quartz crystal, it changes the shape of the crystal itself. If you then squeeze it or bend it, an electric field is generated. When placed in an electronic circuit, the interaction between the mechanical stress and the electrical field causes the crystal to vibrate, generating a constant electric signal which can then be used to measure time. Quartz clocks continue to dominate the market because of the accuracy and reliability of their performance and by their low cost when produced in mass quantities.