The cosmos is one thing.  Where life exists, its living creatures will fit themselves cunningly into each niche where life can be maintained.  On vast green plains there will be animals to graze—­and there will be animals to prey on them.  So the grazing things will band together in herds for self-defense and reproduction.  And where the ground is covered with broad-leaved plants, such plants will shelter innumerable tiny creatures, and some of them will be burrowers.  So rain will drain quickly into those burrowings and not make streams.  And therefore the drainage will reappear as springs, and the grazing animals will go to those springs to drink.  Often, they will gather more densely at nightfall for greater protection from their enemies.  They will even often gather at the springs or their overflowing brooks.  This will happen anywhere that plains and animals exist, on any planet to the edge of the galaxy, because there are laws for living things as well as stones.

Great dark masses of the beasts moved unhurriedly past the ship.  They were roughly the size of cattle—­which itself would be determined by the gravity of the planet, setting a maximum favorable size for grazing beasts with an ample food-supply.  There were thousands and tens of thousands of them visible in the deepening night.  They crowded to the gushing spring and to the stream that flowed from it.  They drank.  Sometimes groups of them waited patiently until the way to the water was clear.

“Well?” said Jones.

“I think you filled my order,” admitted Cochrane.

The night became starlight only, and Cochrane impatiently demanded of Al or somebody that they measure the length of a complete day and night on this planet.  The stars would move overhead at such-and-such a rate.  So many degrees in so much time.  He needed, said Cochrane—­as if this order also could be filled—­a day-length not more than six hours shorter or longer than an Earth-day.

Jones and Al conferred and prepared to take some sort of reading without any suitable instrument.  Cochrane moved restlessly about.  He did not notice Johnny Simms.  Johnny had stood sullenly in his place, not moving to look out the windows, ostentatiously ignoring everything and everybody.  And nobody paid attention!  It was not a matter to offend an adult, but it was very shocking indeed to a rich man’s son who had been able to make a career of staying emotionally at a six-year-old level.

Cochrane’s thoughts were almost feverish.  If the day-length here was suitable, all his planning was successful.  If it was too long or too short, he had grimly to look further—­and Spaceways, Inc., would still not be as completely a success as he wanted.  It would have been much simpler to have measured the apparent size of the local sun by any means available, and then simply to have timed the intervals between its touching of the horizon and its complete setting.  But Cochrane hadn’t thought of it at sunset.