John Clerk o Eldin FRSE FSAScot (10 December 1728 – 10 Mey 1812) wis a Scots merchant, naval author, airtist, geologist an laundawner. He wis a pairt o the Scots Enlichtment, best kent fur his wallie writins on naval tactics in the Age o Sails.
He wis the seivent son o Sir John Clerk o Penicuik, brither-in-law tae airchitect Robert Adam,[1] an great-great-uncle o physicist James Clerk Maxwell.