keen bird, was one of the first voyagers, and
he didn't come back--he stayed there, living in a space-suit for three
or four years, and got a brand-new education. Martian science always
was hot, you know, but they were impractical. They were desperately
hard up for water and air, and while they had a lot of wonderful
ideas and theories, they couldn't overcome the practical technical
difficulties in the way of making their ideas work. Now putting other
peoples' ideas to work was Roeser's long suit--don't think that I'm
belittling Roeser at all, either, for he was a brave and far-sighted
man, was no mean scientist, and was certainly one of the best organizers
and synchronizers the world has ever known--and since Martian and
Tellurian science complemented each other, so that one filled in the
gaps of the other, it wasn't long until fleets of space-freighters were
bringing in air and water from Venus, which had more of both than she
needed or wanted.

"Having done all he could for the Martians and having learned most of
the stuff he wanted to know, Roeser came back to Tellus and organized
Interplanetary, with scientists and engineers on all three planets,
and set to work to improve the whole system, for the vessels they used
then were dangerous--regular mankillers, in fact. At about this same
time Roeser and the Interplanetary Corporation had a big part in the
unification of the world into one nation, so that wars could no longer
interfere with progress."

* * * * *

"With this introduction I can get down to fundamentals. Molecules are
particles of the first order, and vibrations of the first order include
sound, light, heat, electricity, radio, and so on. Second order,
atoms--extremely short vibrations, such as hard X-rays. Third order,
electrons and protons, with their accompanying Millikan, or cosmic,
rays. Fourth order, sub-electrons and sub-protons. These, in the
material aspect, are supposed to be the particles of the fourth order,
and in the energy aspect they are known as Roeser's Rays. That is, these
fourth-order rays and particles seem to partake of the nature of both
energy and matter. Following me?"

"Right behind you," she assured him. She had been listening intently,
her wide-spaced brown eyes fastened upon his face.

"Since these Roeser's Rays, or particles or rays of the fourth order,
seem to be both matter and energy, and since the rays can be converted
into what is supp