Aerial flight is one of that class of problems with which men will never have to cope |
Flight by machines heavier than air is unpractical and insignificant, if not utterly impossible. |
The demonstration that no possible combination of known substances, known forms of machinery and known forms of force, can be united in a practical machine by which men shall fly along distances through the air, seems to the writer as complete as it is possible for the demonstration to be. |
We are probably nearing the limit of all we can know about astronomy. |