Title page of William Thomson's "On the Dynamical Theory of Heat" from Mathematical and Physical Papers.

In famous publications, “On the Dynamical Theory of Heat, with Numerical Results Deduced from Mr Joule’s Equivalent of a Thermal Unit, and M. Regnault’s Observations on Steam” is a March 1851 paper by Irish physicist William Thomson that gave what has come to be known as the Thomson-statement of the second law of thermodynamics. [1] This statement is: [2]

“It it possible to continually get work by abstracting heat from a body till all its heat is removed? Is it possible to get work by cooling a body below the temperature of the medium in which it exists: I believe we may consider a negative answer as axiomatic. Then we deduce the proposition that μ [Carnot’s coefficient] is the same for all substances at a given temperature.”

This was restated again, albeit in simpler terms, in Thomson’s famous 1852 paper “On a Universal Tendency in Nature to the Dissipation of Mechanical Energy.”

References
1. Thomson, William. (1851). “On the Dynamical Theory of Heat, with Numerical Results Deduced from Mr Joule’s Equivalent of a Thermal Unit, and M. Regnault’s Observations on Steam”, Transactions of the Royal Society, March; and Philosophical Magazine, Vol. IV, 1852; and Mathematical and Physical Papers (pgs. 174-315), Vol. 1, 1882.
2. Smith, Crosbie and Wise, M. Norton. (1989). Energy and Empire: a Biographical Study of Lord Kelvin (pg. 329). Cambridge University Press.

External links
● On the Dynamical Theory of Heat (Kelvin papers) – Zapatopi.net.