Kelvin wrote to his nephew William Bottomley mentioning his peerage.
In this letter, William Thomson tells his nephew 'Willie' that 'the Queen confers a peerage of the United Kingdom on me'. He had received the news from Lord Salisbury the previous morning.
Thomson was writing from Broxton Old Hall, Chester, and the letter is dated 31 December 1891. The last page is written by Thomson's wife.
When he was made a peer, Thomson took the name 'Kelvin' because of his connections with Glasgow University. The university sits on the banks of the River Kelvin.
The letter is part of the Bottomley Papers at the National Library of Scotland.