“Fair enough. Does that suit you, Rog? Edie? all right,” as the two nodded, “time for bed. You seem to have the time for the next few days pretty well filled.” The two youngsters grimaced but obeyed; Don and his parents remained. They talked seriously in low tones far into the night. The four younger children had been asleep for several hours when Donald finally climbed the stairs to his room, but the fact did not lessen his caution. He had no desire to spend the rest of the night ducking Roger’s questions about what had gone on downstairs.

In spite of the rather strenuous day just finished, the entire family was up early the next morning. As a “special favor” to his younger brother, Donald volunteered to take the surplus horses back to town — they kept only a few at the summer house, as fodder was a little difficult to obtain. That left the younger boy free, once the shutters were removed from the upstairs windows, to get out on the mapping job, as far as his own work was concerned. Edith was delayed for a while dusting off china and washing cooking utensils — they had cleaned only enough for a sketchy meal the night before — but Roger conquered any slight distaste he might have had for women’s work and helped out. The sun was not yet very high when they emerged onto the porch, consulted briefly, and started uphill around the house.

The boy carried a small Scout compass and a steel tape which had turned up in the basement workshop; his sister had a paper-covered notebook, a school relic still possessed of a few blank pages. Between his father’s teaching and a year in a Scout troop, Roger was sure he could produce a readable map of the stipulated area with no further equipment. He had not considered at all carefully the problem of contours.

High as the Wing house was located, there was still a long climb above it; and both youngsters were quite willing to rest by the time they reached the top. They were willing, too, to sit and look at the view around them, though neither was a stranger to it.

The peaks of the Cabinets extended in all directions except the West. The elevation on which they were located was not high enough to permit them to see very far; but bits of Pend’ Oreille were visible to the southwest and the easily recognized tip of Snowshoe Peak rose between east and south. Strictly speaking, there was no definite timber line; but most of the peaks managed to thrust bare rock through the soil for at least a few hundred feet. The lower slopes were covered with forest, principally the Douglas fir which is so prevalent in the Pacific Northwest. One or two relatively clear areas, relics of forest fires of the last few years, were visible from the children’s point of vantage.

There were a number of points visible within the distance specified by Mr. Wing which looked as though they might serve as reference stations, and presently Roger took out the compass and began taking bearings on as many of these as he could. Edith was already making a free-hand sketch map of their surroundings, and the bearings were entered on this. Distances would come later; Roger knew neither his own altitude nor those of the points he was measuring, and could not have used the information had he possessed it. He knew no trigonometry and had no means of measuring angles of depression.

Details began to crowd the rough chart even before they left the hilltop; and presently the two were completely absorbed in their task. Mrs. Wing was not particularly surprised when they came in late for dinner.

3

The station on Planet One was a decidedly primitive installation, though a good deal of engineering had obviously been needed to make it habitable at all. It was located in the bottom of a deep valley near the center of the planet’s sunward hemisphere, where the temperature was normally around four hundred degrees Centigrade. This would still have been cold enough to liquefy the sulfur which formed the principal constituent of the atmosphere Ken’s people needed; but the additional hundred degrees had been obtained by terracing the valley walls, cutting the faces of the terraces to the appropriate slope, and plating them with iron. The dark-colored metal dome of the station was, in effect, at the focus of a gigantic concave mirror; and between the angular size of sun and the actual size of the dome, solar libration never moved the focus to a serious extent.

The interstellar flyer settled onto a smooth sheet of bare rock beside the dome. There were no cradling facilities, and Ken had to don vacuum armor to leave the vessel. Several other space-suited figures gathered in the airlock with him, and he suspected that most if not all of the ship’s crew were “going ashore” at the same time though, of course, they might not be crew; one operator could