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converting overlapping perspective views into orthophotographic 
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projections on any plane. 
In 1898, Laussedat published a book in which he described his 
research on methods and instruments for the compilation of topographic 
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maps . 
Gaspard-Felix Tournachon (called Nadar) began his career as a 
French caricaturist and journaiist; in 1853, he opened a photographic 
studio in Paris that was to become one of the popular gathering places 
of the city. Nadar had a fine regard for showmanship, as well as his 
reputation. It is not unusual, therefore, that he took up the fashionable 
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sport of ballooning. With the help of the brothers Godard (soon to 
be France's most prominent balloonists) he became a skilled aeronaut 
himself. Inevitably, it occurred to Nadar that he was the first photo 
grapher-aeronaut; in 1856, therefore, he filed a patent on the idea of 
photographing from a balloon. 
His resolve, which was to "get photographic views of the earth at 
a certain height in the air" s was accomplished despite the jeers of scof 
fers. Collodion plates were his biggest difficulty. They had to be 
coated fresh just before exposure, then be shielded from hydrogen gas 
which leaked downward from the balloon, causing unwanted chemical reactions. 
The problem was overcome by constructing, in the airship's basket, a 
darkroom of orange cloth reinforced by a black lining. Late one after 
noon during the summer of 1858, after many repeated failures, Nadar 
ascended once more above Paris. The light proved unsuitable, and he 
had drifted out to the country. So, coming down near Le Petit Bicetre,