Meyer was the first scholar to carry out the experiment of thermal mechanical equivalence, although his experiment was rougher than Joule's. He first expressed the law of conservation of energy: "What shows the absolute truth of my law is this opposite proof: a scientifically recognized theorem: the design of perpetual motion machine is absolutely impossible in theory."

1858 Helmholtz read Meyer's 1852 paper and admitted that Meyer's thought was earlier than his own widely influential paper. Clausius also thinks that Meyer is the discoverer of conservation law.

Extended data:

From18th century to19th century, natural science was dominated by the theory of heat and mass for a long time. This one-sided theory holds that there is a fluid in matter called thermal mass. The heat transfer caused by temperature difference is regarded as the thermal mass flowing from high-temperature objects to low-temperature objects; Friction heat generation is considered to be the result of heat and mass release. This theory contradicts many experimental facts.

During the period of 1798, the barrel was developed in langford, and it was observed that the heat generated was not proportional to the amount of metal chips removed by drilling and grinding. In addition, if drilling and grinding are continued with a blunt drill, the heat released is almost infinite, which indicates that the thermal mass cannot be a substance.

Later, after the work of H. David, J. Mayer and H. Helmholtz, especially the thermal mechanical equivalent experiment conducted by J. Joule during 1840- 1848, people gradually realized that thermal mass did not exist. The transfer or transformation of heat is the same as the transfer or transformation of mechanical work and electrical work, and the total energy is constant in the process of transfer or transformation.

Reference source: Baidu Encyclopedia-Law of Conservation of Energy

Reference source: Baidu Encyclopedia -Meyer, J R.