1856-1920 1866-1955 1873-1933 1874-1922 20thcentury adventurers autobiography biography britishantarcticexpedition(1907-1909) descriptionandtravel difficultyofascent discoveryandexploration ernesthenry explorers henson history luigiamedeodi matthewalexander modern mountaineering mountaineeringaccidents mountaineeringexpeditions mountaineers mountains pakistan peary polarregions savoia shackleton travel