|Title page of William Thomson's "On a Universal Tendency" from Mathematical and Physical Papers.|
The following noted quote is a view that eventually became synonymous with heat death: 
“Within a finite period of time past, the earth must have been, and within a finite period of time to come the earth must again be, unfit for the habitation of man as at presented constituted, unless operations have been, or are to be performed, which are impossible under laws to which the known operations going on at present in the material world are subject.”
This paper is often the considered as the softer verbal description of German physicist Rudolf Clausius' more dense mathematical description of the second law. In fact, what has been termed the law of dissipation originated in "On a Universal Tendency", and it is colloquially assumed that the second law is simply a mathematical statement of the law of dissipation. American historian Henry Adams used Thomson’s “On a Universal Tendency” paper as his key second law reference in his famous A Letter to American Teachers of History to argue that society, history, and evolution are subject to the laws of thermodynamics. He states: 
“The second law of thermodynamics was briefly stated by Thomson in “On a Universal Tendency in Nature to the Dissipation of Mechanical Energy”, published in October, 1852, which is now as classic as Kepler’s or Newton’s Laws.”
This has come to be known as the Kelvin statement of the second law of thermodynamics.  This enunciation had previously been stated in the form of a question by Thomson in his 1851 paper “On the Dynamical Theory of Heat”: 
“It is 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.”
1. (a) Thomson, William. (1852). "On a Universal Tendency in Nature to the Dissipation of Mechanical Energy", Proceedings of the Royal Society of Edinburgh for April 19; also Philosophical Magazine, Oct. 1852; also Mathematical and Physical Papers (pgs. 511-14), vol. i, art. 59.
(b) Lindberg, David C., Porter, Roy, Nye Mary J., Numbers, Ronald L, and Ross, Dorothy. (2003). The Cambridge History of Science: the Modern Physical and Mathematical Sciences (pg. 300). Cambridge University Press.
2. Hokikian, Jack. (2002). The Science of Disorder: Understanding the Complexity, Uncertainty, and Pollution in Our World (pg. 52). Los Feliz Publishing.
3. Adams, Henry. (1910). A Letter to American Teachers of History (ch. 1, pg. 2). Google Books, Scanned PDF. Washington.
4. (a) 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.
(b) Smith, Crosbie and Wise, M. Norton. (1989). Energy and Empire: a Biographical Study of Lord Kelvin (pg. 329). Cambridge University Press.
● On a Universal Tendency – Zapatopi.net.