In 1858, he became the first person to take aerial photographs. This was done using the wet plate collodion process, and since the plates had to be prepared and developed (a process that required a chemically neutral setting) while the basket was aloft, Nadar experienced imaging problems as gas escaped from his balloons. After Nadar invented a gas-proof cotton cover and draped it over his balloon baskets, he was able to capture stable images. He also pioneered the use of artificial lighting in photography, working in the catacombs of Paris. He was thus the first person to photograph from the air with his balloons, as well as the first to photograph underground, in the Catacombs of Paris. In 1867, he published the first magazine to focus on air travel: "L'Aéronaute".