There were still significant explorations which occurred well into the modern age. This includes the Lewis and Clark expedition (1804-1806), an overland expedition dispatched by President Thomas Jefferson to explore the newly acquired Louisiana Purchase and to find an interior aquatic route to the Pacific Ocean, along with other objectives to examine the flora and fauna of the continent. In 1818, the British researcher Sir John Ross was the first to find that the deep sea is inhabited by life when catching jellyfish and worms in about depth with a special device. The United States Exploring Expedition (1838-1842) was an expedition sent by President Andrew Jackson, in order to survey the Pacific Ocean and surrounding lands.