Semester at Sea Atlantic or west across the Pacific, visiting from 10 to 11 countries in Asia, Africa, Europe, South America and North America. The program previously had voyages that would sail through the Mediterranean and the Suez Canal, but due to piracy concerns in the Gulf of Aden, voyages now typically travel around Africa. For many years, ISE hosted a shorter 65-day Semester at Sea program in the summer that concentrated on one general region of the world. In May 2011, Semester at Sea introduced a new short-term or Maymester voyage with a curriculum focused on the UN Millennium Development Goals. These
Iron metallurgy in Africa 20th century in many parts of sub-Saharan Africa, whereas in Europe and most parts of Asia they were replaced by the blast furnace before most varieties of bloomeries could be recorded. W.W. Cline's compilation of eye-witness records of bloomery iron smelting over the past 250 years in Africa is invaluable, and has been supplemented by more recent ethnoarchaeological and archaeological studies. Furnaces used in the 19th and 20th centuries ranges from small bowl furnaces, dug down from the ground surface and powered by bellows, through bellows-powered shaft furnaces up to 1.5 m tall, to 6.5m natural-draft furnaces (i.e. furnaces designed