Boart Longyear samples for the proposed Golden Gate Bridge in San Francisco. In spite of the financial crisis, the 1930s saw improvements in diamond drilling technology, including the use of industrial-quality diamonds mined in Africa that were called “boarts.” In 1936, South Africa’s Anglo American Corporation formed Boart Products South Africa (Pty) Limited, which was later named Boart International. The new company developed the first mechanically-set diamond core bits, which were less expensive than the hand-set core bits that used more expensive Brazilian diamonds (carbonados). Longyear’s business gradually improved in the 1940s in response to expanding worldwide mineral exploration. In 1949, the
Léon Teisserenc de Bort Léon Teisserenc de Bort Léon Philippe Teisserenc de Bort (5 November 1855 in Paris, France – 2 January 1913 in Cannes, France) was a French meteorologist and a pioneer in the field of aerology. Together with Richard Assmann (1845-1918), he is credited as co-discoverer of the stratosphere, as both men announced their discovery during the same time period in 1902. Teisserenc de Bort pioneered the use of unmanned instrumented balloons and was the first to identify the region in the atmosphere around 8-17 kilometers of height where the lapse rate reaches zero, known today as the tropopause. He was the