
A 1894 summary of the perpetual motion of the second kind (II), by American physicist J.E. Trevor. [1]

A 1894 summary of the perpetual motion of the second kind (II), by American physicist J.E. Trevor. [1]

In motion classifications, perpetual motion of the second kind refers to perpetual motion machines or perpetual motion theories that violate the second law of thermodynamics.

In lay terms, perpetual motion of the second kind refers to theories or devices that purport to transform energy without intensity differences, such as gaining work from the constant temperature of a mass of water. [1]

An example of "perpetual mobile of the second kind" would be a device that purports to convert the supply of energy related to temperature contained in the soil, water, or atmosphere, where are practically unlimited, into use work. [3] This type of perpetual motion machine is said to be a violation of William Thomson's version of the second law:

“A transformation whose only final result is to transform into work heat extracted from a source which is at the same temperature throughout is impossible.”

This is said to be equivalent to the same version of the statement made by Rudolf Clausius: [3]

“A transformation whose only final result is to transfer heat from a body at a given temperature to a body at a higher temperature is impossible.”

Etymology
The classification of perpetual motion of the "second" kind seems to trace to German physical chemist Wilhelm Ostwald’s 1893 Textbook of General Chemistry, wherein he outlined the so-called two laws of energetics. [2]

References
1. Trevor, J.E. (1894). “Book review: Lehrbuch der Allgemeinen Chemie”, The Physical Review . MacMillan and Company.
2. Ostwald, Wilhelm. (1893). Textbook of General Chemistry (Lehrbuch der Allgemeinen Chemie). Leipzig: W. Engelmann.
3. Fermi, Enrico. (1936). Thermodynamics (pg. 29). Prentice Hall.

Further reading
● Wainwright, Jacob T. (1905). Perpetual Motion of the Second Kind: or Heat from the Atmosphere a Substitute from Fuel. M. A. Donohue Printers.

External links
● Perpetual motion of the second kind (section) – Wikipedia.