Virgin Group chairman Sir Richard Branson, joined by former Vice President Al Gore and other leading environmentalists, announced a $25 million prize for the scientist who comes up with a way of extracting(抽出する)greenhouse gases from the atmosphere. Branson compared the contest to a competition launched(着手する)in 1675 to devise a method of estimating longitude(経度)accurately. It was 60 years before English clockmaker John Harrison discovered an accurate method and received his prize from King George III.