 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.A closer examination of the quality of la Cour's wind tunnel shows that the wind speed varies with a factor 2 form the centre line to the edge, thus putting some inaccuracy to his results.