most important discovery.

The Cavour Hyperdrive unquestionably would have held first rank in any
historical assessment, had the Cavour Hyperdrive ever reached practical
use. The Lexman Spacedrive allows mankind to reach Alpha Centauri, the
closest star with habitable planets, in approximately four and a half
years. The Cavour Hyperdrive--if it ever really existed--would have
brought Alpha C within virtual instantaneous access.

But James Hudson Cavour had been one of those tragic men whose
personalities negate the value of their work. A solitary, cantankerous,
opinionated individual--a crank, in short--he withdrew from humanity to
develop the hyperspace drive, announcing at periodic intervals that he
was approaching success.

A final enigmatic bulletin in the year 2570 indicated to some that
Cavour had achieved his goal or was on the verge of achieving it;
others, less sympathetic, interpreted his last message as a madman's
wild boast. It made little difference which interpretation was accepted.
James Hudson Cavour was never heard from again.

A hard core of passionate believers insisted that he _had_ developed a
faster-than-light drive, that he had succeeded in giving mankind an
instantaneous approach to the stars. But they, like Cavour himself, were
laughed down, and the stars remained distant.

Distant--but not unreachable. The Lexman Spacedrive saw to that.

Lexman and his associates had developed their ionic drive in 2337, after
decades of research. It permitted man to approach, but not to exceed,
the theoretical limiting velocity of the universe: the speed of light.

Ships powered by the Lexman Spacedrive could travel at speeds just
slightly less than the top velocity of 186,000 miles per second. For the
first time, the stars were within man's grasp.

The trip was slow. Even at such fantastic velocities as the Lexman
Spacedrive allowed, it took nine years for a ship to reach even the
nearest of stars, stop, and return; a distant star such as Bellatrix
required a journey lasting two hundred fifteen years each way. But even
this was an improvement over the relatively crude spacedrives then in
use, which made a journey from Earth to Pluto last for many months and
one to the stars almost unthinkable.

The Lexman Spacedrive worked many changes. It gave man the stars. It
brought strange creatures to Earth, strange products, strange languages.

But one necessary factor was involved in slower-than-light inters