At a time when attempts were being made to use the largest possible wheels to achieve high speeds while keeping the center of gravity low, some curious designs emerged. In 1855 Blavier and Larpent built the “L'Aigle” (“The Eagle”) with 9 ft 4 in wheels on the French Ouest. Their goal was to double the speed of the Cramptons. Since these had already reached 120 km/h at that time, this goal was hardly realistic to achieve.

With this wheel diameter, a boiler, which was usually above the axles, would have been very high above the top of the rails. At that time, everyone was convinced that a low center of gravity was the most important criterion for smooth running and developed many long boiler type locomotives, which had a thin and long, overhanging boiler to achieve the lowest possible center of gravity. Since this was not possible with the “L'Aigle”, completely new paths were taken.

Section through the special, two-part boiler

Locomotive Magazine, December 1901

The actual boiler, with a small diameter, lay below the axles and was connected to a second, cylindrical barrel, which lay above the axles. Although the boiler had sufficient volume, there were no smoke tubes in the upper boiler body. This made it impossible to produce enough steam for the large cylinders at higher speeds. Thus, the one-off never made it into commercial service and the allegedly achieved speed of 100 mph must be doubted.