r best bet would be to take all the books
we can--making sure we get the introductory ones, so we can read the
language.

"See--over there--they have marked those shelves with a single vertical
mark. The ones next to them have two vertical marks, and next ones
three. I suggest we load up with those books and take them to the ship."

The rest agreed, and they began carrying armloads of books, flying out
through the top of the pyramid to the ship and back for more.

Instead of flying back to the pyramid for the last load, Arcot announced
that he was going to leave a note for anyone who might come here later.
While the others went back for the last load, he worked at drawing the
"note".

"Let's see your masterpiece," said Morey as the three men returned to
the ship with the last of the books.

Arcot had used a piece of tough, heavy plastic which would resist any
corrosion the cold, almost airless world might have to offer.

Near the top, he had drawn a representation of their ship, and beneath
it a representation of the route they had taken from universe to
universe. The galaxy they were in was represented by a cloud of gas, its
main identifying feature. Underneath the dotted line of their route
through space, he had printed "200,000,000,000, _u_".

Then followed a little table. The numeral "1" followed by a straight
bar, then "2" followed by two bars, and so on up to ten. Ten was
represented by ten bars and, in addition, an S-shaped sign. Twenty was
next, followed by twenty bars and two S-shaped signs. Thus he had
worked up to "100".

The system he used would make it clear to any reasoning creature that he
had used a decimal system and that the zeroes meant ten times.

Next below, he had drawn the planetary system of the frozen world, and
the distance from the planet they were on to the central sun he labeled
"_u_". Thus, the finders could reason that they had come a distance of
two hundred billion units, where a distance of three hundred million
miles was taken as the unit; they had, then, come from another galaxy.
Certainly any creature with enough intelligence to reach this frozen
world would understand this!

"Since the year of this planet is approximately eight times our own,"
Arcot continued, "I am indicating that we came here approximately five
hundred years after the catastrophe." He pointed at several of the other
drawings.

They left the message in the tower, and Arcot closed the door, leaving
the