Wilbur and Orville recorded the measurements they made with their first wind tunnel on scraps of wallpaper they laid in the bottom of the tunnel, including these pieces. The brothers used the tunnel only for a day, but their results again showed clear discrepancies with Lilienthal’s data.

After building and testing a small wind tunnel, the Wright brothers completed a larger, more sophisticated one in October 1901. They used it extensively to carry out aerodynamic research that proved essential in designing their 1903 airplane.
 
The wind tunnel consisted of a simple wooden box with a square glass window on top for viewing the interior during testing. A fan belted to a one-horsepower engine, which ran the machinery in their bicycle shop, provided an airflow of about 30 miles per hour.

What made the Wrights’ wind tunnel unique were the instruments they designed and built to measure lift and drag. Called balances, after the force-balancing concept, these instruments measured the forces of lift and drag acting on a wing in terms that could be used in the equations.
 
The balances are made from old hacksaw blades and bicycle spokes. Their crude appearance belies their sophisticated design. Largely the work of Orville, they represent a solid understanding of geometry, mathematics, and aerodynamic forces, and illustrate the Wrights’ engineering talents at their finest.