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Hot-air Balloons
b) The 'Stratoscope' flights of 1959, concerned mainly with studies of the Sun, were remarkably successful.
d) The main development has been carried out by M. Schwarlschild and his team at Princeton University in the United States, in collaboration with the United States Navy.
c) Hot-air balloons date back to the year 1783, and within a few months of the first flight a French scientist, Charles, went up two miles in a free balloon.
a) Yet there is little resemblance between these crude vehicles and a modern scientific balloon, which has by now become an important tool.
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