Towards the end of his life he returned to studying the movement of quite abstract forms, like a falling ball. His last great work was the observation and photography of smoke trails. This research was partially funded by Samuel Pierpont Langley under the auspices of the Smithsonian Institution, after the two met in Paris at the Exposition Universelle (1900). In 1901 he was able to build a smoke machine with 58 smoke trails. It became one of the first aerodynamic wind tunnels.