Lord Kelvin (1824-1907) attempts to find the age of the Earth by examining its cooling time and estimates that the Earth is between 20-400 million years old.
Editors. "Age of Earth estimated". The Literary Encyclopedia. First published 01 May 2009; last revised 30 November -1.
[http://www.litencyc.com/php/stopics.php?rec=true&UID=6324, accessed 26 April 2015.]