Other notable alumni and academic staff of the university have included signatories to the US Declaration of Independence Benjamin Rush, James Wilson and John Witherspoon, actor Ian Charleson, architects Robert Adam and William Henry Playfair, astronaut Piers Sellers, biologists Sir Richard Owen and Sir Ian Wilmut, composer Marjory Kennedy-Fraser, economists Thomas Chalmers and Adam Smith, historian Thomas Carlyle, journalist Laura Kuenssberg, judge Robert Reed, mathematicians Colin Maclaurin and John Playfair, philosophers Benjamin Constant, Adam Ferguson, David Hume and Dugald Stewart, physician William Cullen, pilot Eric Brown, surgeons James Barry and B. K. Misra, writers Sir J.M. Barrie, Sir Arthur Conan Doyle, Sir Walter Scott, Robert Louis Stevenson and Aeneas Francon Williams, former Chancellors of the Exchequer John Anderson and Henry Petty, former Deputy Prime Minister of New Zealand Sir Michael Cullen, former Director General of MI5 Stella Rimington, former First Lord of the Admiralty Lord Melville, former acting First Minister of Scotland Jim Wallace, and Olympic gold medallists Katherine Grainger, Sir Chris Hoy, and Eric Liddell.