begin to resist the necessary pressure. Our
aerial ship must be filled with some substance lighter than air.
Whether heated air would answer the purpose, or whether we should have
to use a gas, is a question for the designer.

To return to our main theme, all should admit that if any hope for the
flying-machine can be entertained, it must be based more on general
faith in what mankind is going to do than upon either reasoning or
experience. We have solved the problem of talking between two widely
separated cities, and of telegraphing from continent to continent and
island to island under all the oceans--therefore we shall solve the
problem of flying. But, as I have already intimated, there is another
great fact of progress which should limit this hope. As an almost
universal rule we have never solved a problem at which our predecessors
have worked in vain, unless through the discovery of some agency of
which they have had no conception. The demonstration that no possible
combination of known substances, known forms of machinery, and known
forms of force can be united in a practicable machine by which men
shall fly long distances through the air, seems to the writer as
complete as it is possible for the demonstration of any physical fact
to be. But let us discover a substance a hundred times as strong as
steel, and with that some form of force hitherto unsuspected which will
enable us to utilize this strength, or let us discover some way of
reversing the law of gravitation so that matter may be repelled by the
earth instead of attracted--then we may have a flying-machine. But we
have every reason to believe that mere ingenious contrivances with our
present means and forms of force will be as vain in the future as they
have been in the past.

End of the Project Gutenberg EBook of Side-lights on Astronomy and Kindred
Fields of Popular Science, by Simon Newcomb

*** END OF THIS PROJECT GUTENBERG EBOOK SIDE-LIGHTS ON ASTRONOMY ***

***** This file should be named 4065.txt or 4065.zip *****
This and all associated files of various formats will be found in:
http://www.gutenberg.org/4/0/6/4065/

Produced by Charles Franks, Robert Rowe and the Online
Distributed Proofreading Team. HTML version by Al Haines.

Updated editions will replace the previous one--the old editions
will be renamed.

Creating the works from public domain print editions means that no
one owns a United States copyright in