"If its engine stops, it must fall with deathly violence, for it can neither glide like the aeroplane or float like the balloon. The helicopter is much easier to design than the aeroplane, but is worth…"

"Our confidence in the ability of men to fly has not been shaken."

"Success in inventing depends on the close observation of nature."

"We have been very busy with the manufacture of our machines."

"We could not understand why the calculation of Lilienthal and others were so much in error."