The brothers scrambled out and surveyed the situation. George swore lustily, voice more thickly accented than ever.

'B' Jupe 'n' domn, we're in a pickled situation f'r fair. 'Tis wallowing in the mud there like a blasted pig.'

Allen shoved his hair back wearily, 'Well, don't stand there looking at it. We're still a hundred miles or better from Areso-polis. We've got to get it out of there.'

'Sure, but how?' His imprecations dropped to sibilant breathings as he reached into the truck for the coil of rope in the back. He looked at it doubtfully.

'Y' get in here, All'n, and when I pull, press down with y'r foot on that pedal.'

He was tying the rope to the front axle even as he spoke. He played it out behind him as he slogged out through ankledeep mud, and stretched it taut.

'All right, now, give I' he yelled. His face turned purple with effort as his back muscles ridged. Allen, within the car, pressed the indicated pedal to the floor, heard a loud roar from the engine and a spinning whir from the back wheels. The truck heaved once, and then sank back.

''Tis no use,' George called. 'I can't get a footing. If the ground were dry, I c'd do it.'

'If the ground were dry, we wouldn't be stuck,' retorted Allen. 'Here, give me that rope.'

'D y' think y' can do it, if / can't?' came the enraged cry, but the other had already left the car.

Allen had spied the large, deep-bedded boulder from the truck, and it was with relief that he found it to be within reaching distance of the rope. He pulled it taut and tossed its free end about the boulder. Knotting it clumsily, he pulled, and it held.

His brother leaned out of the car window, as he made his way, back, with one lumped Ganymedan fist agitating the air.

'Hi, y' nitwit. What're y' doing? D' y' expect that overgrown rock t' pull us out?'

'Shut up,' yelled back Allen, 'and feed her the gas when I pull.'

He paused midway between boulder and truck and seized the rope.

'Give!' he shouted in his turn, and with a sudden jerk pulled the rope toward him with both hands.

The truck moved; its wheels caught hold. For a moment it hesitated with the engine blasting ahead full speed, and George's hands trembling upon the wheel. And then it went over. And almost simultaneously, the boulder at the other end of the taut rope lifted out of the mud with a liquid smacking sound and went over on its side.

Allen slipped the noose off it and ran for the truck.

'Keep her going,' he shouted, and hopped onto the running board, rope trailing.

'How did y' do that?' asked George, eyes round with awe.

'I haven't got the energy to explain it now. When we get to Aresopolis and after we've had a good sleep, I'll draw the triangle of forces for you, and show you what happened. No muscles were involved. Don't look at me as if I were Hercules.'

George withdrew his gaze with an effort, 'Triangle o' forces, is it? I never heard o' it, but if that's what it c'n do, education's a great thing.'

'Comet-gas! Is any coffee left?' He stared at the last thermos-bottle, shook it near his ear dolefully, and said, 'Oh, well, let's practice the quaver. It's almost as good and I've practically got it perfected.'

He yawned prodigiously, 'Will we make it by nightfall?'

'Maybe!'

The canal was behind them now.

The reddening sun was lowering itself slowly behind the Southern Range. The, Southern Range is one of the two 'mountain chains' left on Mars. It is a region of hills; ancient, time-worn, eroded hills behind which lies Aresopolis.

It possesses the only scenery worth mentioning on all Mars and also the golden attribute of being able, through the up-drafts along its sides to suck an occasional rain out of the desiccated Martian atmosphere.

Ordinarily, perhaps, a pair from Earth and Ganymede might have idled through this picturesque area, but this was definitely not the case with the Carter twins.

Eyes, puffed for lack of sleep, glistened once more at the sight of hills on the horizon. Bodies, almost broken for sheer weariness, tensed once more when they rose against the sky.

And the truck leaped ahead, - for just behind the hills lay Aresopolis. The road they traveled was no longer a rule-edge straight one, guided by the compass, over table-top-flat land. It followed narrow, twisting trails over rocky ground.

They had reached Twin Peaks, then, when there was a sudden sputter from the motor, a few halting coughs and then silence.

Allen sat up and there was weariness and utter disgust in his voice, 'What's wrong with this everlastingly-to-be-damned machine now?'

His brother shrugged, 'Nothing that I haven't been expecting for the last hour. We're out o' gas. Doesn't matter at all. We're at Twin Peaks - only ten miles fr'm the city. We c'n get there in an hour, and then they c'n send men out here for the blooms.'

'Ten miles in an hour!' protested Allen. 'You're crazy.' His face suddenly twisted at an agonizing thought, 'My God! We can't do it under three hours and it's almost night. No one can last that long in a Martian night. George, we're -'

George was pulling him out of the car by main force, 'By Jupe 'n' domn, All'n, don't let the tenderfoot show through now. We c'n do it in an hour, I tell y'. Didn't y' ever try running under sub-normal gravity? It's like flying. Look at me.'

He was off, skimming the ground closely, and proceeding in ground-covering leaps that shrank him to a speck up the mountain side in a moment.

He waved, and his voice came thinly, 'Come on!'

Allen started, - and sprawled at the third wild stride, arms flailing and legs straddled wide. The Ganymedan's laughter drifted down in heartless gusts.

Allen rose angrily and dusted himself. At an ordinary walk, he made his way upwards.

'Don't get sore, All'n,' said George. 'It's a knack, and I've had practice on Gannie. Just pretend y'r running along a feather bed. Run rhythmically - a sort o' very slow rhythm -and run close t' the ground; don't leap high. Like this. Watch me!'

The Earthman tried it, eyes on his brother. His first few uncertain strides became surer and longer. His legs stretched and his arms swung as he matched his brother, step for step.

George shouted encouragement and speeded his pace, 'Keep lower t' the ground, All'n. Don't leap 'fore y'r toes hit the ground.'

Allen's eyes shone and, for the moment, weariness was forgotten, 'This is great! It is like flying - or like springs on your shoes.'

'Y' ought t' have lived on Gannie with me. We've got special fields f'r subgravity races. An expairt racer c'n do forty miles an hour at times - and I c'n do thirty-five myself. - O' course, the gravity there's a bit lower than here on Mars.'

Long hair streamed backwards in the wind and skin reddened at the bittercold air that blew past. The ruddy patches of sunlight traveled higher and higher up the slopes, lingered briefly upon the very summits and went out altogether. The short Martian twilight started upon its rapidly darkening career. The Evening Star - Earth - was already glimmering brightly, its attendant moon somewhat closer than the night previous.

The passing minutes went unheeded by Allen. He was too absorbed by the wonderful new sensation of sub-gravity running, to do anything more than follow his brother. Even the increasing chilliness scarcely registered upon his consciousness.

It was George, then, upon whose countenance a tiny, puckered uneasiness grew into a vast, panicky frown.

'Hi, All'n, hold up!' he called. Leaning backward, he brought himself to a short, hopping halt full of grace and ease. Allen tried to do likewise, broke his rhythm and went forward upon his face. He rose with loud reproaches.

The Ganymedan turned a deaf ear to them. His gaze was sombre in the dusk, 'D' y' know where we are, All'n?'