. At a hundred thousand feet, upon all the
Great Circle routes, liners were rushing at nearly a thousand miles an
hour. They would halt at intervals, to allow helicopter tenders to
come up to transfer descending passengers.

Then the etheric wave-thrust principle was discovered: by 2500 A.D.
man was voyaging out into space and Interplanetary travel began. This
brought new problems: a rush of new millions of humans to live upon
our Earth; new wars; new commerce in peace times; new ideas; new
scientific knowledge....

By 2500, the city around Larry must have reached its height. It stayed
there a half century; and then it began coming down. Its degeneration
was slow, in the beginning. First, there might have been a hole in the
arcade which was not repaired. Then others would appear, as the
neglect spread. The population left. The great buildings of metal and
stone, so solidly appearing to the brief lifetime of a single
individual, were impermanent over the centuries.

By 2600, the gigantic ghosts had all melted down. They lay in a
shadowy pile, burying the speeding cage. There was no stopping here;
there was no space unoccupied in which they could stop. Larry could
see only the tangled spectres of broken, rusting, rotting metal and
stone.

He wondered what could have done it. A storm of nature? Or had mankind
strangely turned decadent, and rushed back in a hundred years or so to
savagery? It could not have been the latter, because very soon the
ruins were moving away: the people were clearing the city site for
something new. For fifty years it went on.

* * * * *

Tina explained it. The age of steam had started the great city of New
York, and others like it, into its monstrous congestion of human
activity. There was steam for power and steam for slow transportation
by railroads and surface ships. Then the conquest of the air, and the
transportation of power by electricity, gradually changed things. But
man was slow to realize his possibilities. Even in 1930, all the new
elements existed; but the great cities grew monstrous of their own
momentum. Business went to the cities because the people were there;
workers flocked in because the work was there to call them.

But soon the time came when the monster city was too unwieldy. The
traffic, the drainage, the water supply could not cope with
conditions. Still, man struggled on. The workers were mere
automatons--pallid attendants of machi