Sir Roderick Impey Murchison was the renowned geologist who identified the Silurian system. An important milestone in geology, it established the oldest fossil-bearing bedrock then known. After an unpromising start in life, Murchison?s fortunes changed in 1825 when he was admitted into the Royal Institution as a fellow of the Geological Society. He quickly became one of the most prominent members of the Society. In this fine mezzotint a copy of his book "The Silurian System" can be seen resting on his lap. However, Murchison is perhaps best known for his contribution to British imperial expansion. As president of the Royal Geographical Society (RGS), which he helped found, he was able to shape much of Britain?s overseas research effort, both in the official empire and beyond. David Livingstone dedicated his best-selling "Missionary Travels" (1857) to him in recognition of the powerful influence which he commanded in London?s scientific and political communities. Today more than twenty geographical features around the world are named in Murchison?s honour.