After only a few weeks of experiments la Cour came to the general conclusions that are still accepted: to produce a maximum of energy with a given wing area, the number of wings should be small, their bevel small and the speed of rotation fast. A few years later he presented his results to an audience of engineers: working with the a standard size wing he found that under optimal conditions 8 wings would absorb 28% of the total energy passing swept area, and 16 wings only slightly better (29%), and even 4 wings were fairly good (21%). In a calculation based on the particle conception of wind, he found that the four wings could absorb 144% of the energy which struck them, which of course is impossible. He concluded that in general all former theories and formulae concerning wings seemed to be incorrect; and to the extent they were correct, gave no information of any practical importance to the millwright.