Extensometer
（重定向自Laser Extensometer）
![A wireline extensometer monitoring slope displacement and transmitting data remotely via radio or Wi-Fi](/Images/godic/202501/23/SlideMinder_Extensometer1421.png")
![Non-contact extensometer for tensile testing](/Images/godic/202501/23/Non_contact_extensometry31422.JPG")
An extensometer is a device that is used to measure changes in the length of an object. It is useful for stress-strain measurements and tensile tests. Its name comes from "extension-meter". It was invented by Charles Huston who described it in an article in the Journal of the Franklin Institute in 1879. Huston later gave the rights to Fairbanks & Ewing, a major manufacturer of testing machines and scales.