"Lead off, Dr. Patterson," Troy called out over the car radio.

Alec increased power and the track of his Sno car dug into the soft surface, then caught and the vehicle moved forward and into the trees.

Troy fell into line behind the other vehicle as they drove down the gentle slope towards the snow-covered access trail another mile below them on the side of the mountain.

Out of the trees and onto the trail, both drivers shifted gears, dropping rear skis to the more solid pack of the trail and sending jets of steam shooting out from the thrust tubes of the Sno cars. Troy dropped back to stay out of Alec's vapor cloud as they now glided smoothly and easily along the trail. A bright red metal pole, topped by a small housing and antenna came into view on the side of the road.

The tube went down through the snow and deep into the soil of the mountain side. Inside, electrostats read soil moisture at depths up to thirty feet and transmitted the information on automatic or demand signal.

Ahead, the vapor cloud from Alec's Sno car vanished as the trail dipped down the side of the mountain and the driver cut his thrust to let the momentum carry him on the twin set of skis. Troy gunned his car for a final burst of speed then cut rear drive and dropped swoopingly down the grade, whipping along in Alec's tracks. The trail curved sharply ahead and Troy gently manipulated the front fork skis into a snowplow to cut speed. His fingers rested lightly on the pressure switch that would open small scoops on the under surfaces of all skis for additional braking power. As a final resort, the engine thrust could be shifted from rear to forward reaction to bring him to a complete stop and even send the car backwards.

The Sno car whipped around and down the trail. As the roadway swung to the south slope of the range, the track in the fresh snow cut by the lead vehicle turned dark gray and then almost black. When the present storm had ended and before new snow fell again, the south slopes would again be stained with clouds of black, mono-molecular film, gushing out in clouds behind spray jets of the survey planes. Each successive layer was treated, lessening the evaporative surface effects of the sun upon the south slopes and holding as much of the moisture-giving snow to the earth for controlled runoff. A pair of fresh elk-tracks came down the side of the mountain and cut across the trail and Troy braked to peer through the trees for a glimpse of the animals. But they had vanished, frightened by the sudden intrusion of the men.

A half hour later and four thousand feet lower, the trail joined a wider and more traveled road. Alec turned onto the road and increased speed. A few minutes later, the Sno cars flashed by a sign reading "Elk City--4 miles." Alec cut speed and waited for Troy to pull alongside, then the two cars glided slowly to the edge of the wilderness community. At the outskirts of the little town the snow on the road came to an abrupt end. Chemically-treated paving kept the roadways warm and bare of snow. Ahead, the pavement into town was wet and glistening and even falling snow had stopped. Rear skis were again retracted and the front wheels lowered for non-snow driving and then the two vehicles rumbled slowly into Elk City.

They came to a halt at the ranger station and dismounted.

"Let's call for a taxi and then go for a cup of coffee and another bite," Troy said. "I'm starved again."

"You and that hollow stomach to match your head," Alec grunted.

They entered the ranger station. Behind the counter, one of the four rangers on permanent duty at the station was transferring a radar storm plot onto a weather chart. He glanced up as the two men entered.

"Back so soon," he commented. "That was a quick trip. Get the job done?"

"Neither rain, snow or sun stops the Division of Agriculture in its appointed rounds," Troy said flippantly. "Harry, call Spokane and tell 'em we're ready for a pickup, please."

The ranger reached for a mike. "Spokane Region," he called, "this is Elk City station."

"This is Spokane," came the reply.

"Your two snow boys are here," Harry said, "looking for a lift. Can you send a 'copter after them?"

"Affirmative, Elk City," Spokane communicator replied. "We'll pick them up in about forty-five minutes."

"Thanks, Harry," Troy said. "We're going to take a walk uptown and get something to eat. If the chopper should get here sooner, tell him we'll be right back."

"O.K.," the ranger said, "but there's a pot of coffee on the stove in the kitchen if you want to save yourself the walk."

Alec grimaced. "I had a cup of that concentrated sulphuric acid you call coffee on the way up," he said. "No thanks, anyway. What do you make that stuff out of? Leftover road oil?"

"Man's drink for a real man," the ranger grinned. "Us forestry men learn to make coffee from pine pitch. Makes a man outta you."

"Huh," Alec sniffed as they turned to leave, "pine pitch is just sap and anyone who'd drink that stuff deserves the name--'sap' that is."

The ranger grinned as the hydrologists walked out.

Troy and Alec were walking back up the street to the station when the big cargo copter settled down to the pad at the rear of the station.

They hurried their pace and got to their Sno cars. By the time they had driven around to the pad, the copter crew had lowered the ramp and they drove directly up and into the craft. A row of front-wheel racks studded the after wall of the cargo deck and Troy and Alec nosed their Sno cars into the racks. By the time they had cut power and climbed out, the crewmen had cargo locks on both vehicles.

The crew chief closed the ramp and punched a signal b.u.t.ton. As Troy and Alec climbed up the gangway to the crew-pa.s.senger deck, the big jet rotors were already churning and the copter lifted into the again lightly falling snow.

The hydrologists settled into seats for the short ride to Spokane. The copter swung to the northwest, roaring a thousand feet above the snow-covered mountain tops. They soared over the Clearwater River that flowed to its confluence with the once-mighty Snake River at Lewiston where both vanished into a subterranean aqueduct. As they neared Spokane, the country began to flatten out into the great Columbia basin, where once nearly a fifth of the nation's entire electrical output was produced in a series of hydroelectric dams on the great river and its tributaries. A century ago, high tension power transmission lines and towers laced the face of the nation, carrying power from the waterways to the wheels of industry and cities hundreds of miles away. Like the dams, they, too, were gone and each industry and metropolis and village generated its own power with compact nuclear reactors.

The copter dropped down into an airways lane as it came over the edge of the suburbs of Greater Spokane. The air lane followed almost directly above one of the crowded ten-lane North American Continental Thruways that cut five-mile wide swaths across the continent from Fairbanks to the southern borders of Mexico; from San Francisco to Washington, D.C., and from Montreal to Vancouver.

As the chopper settled down over the heliport at Region Six headquarters, Troy and Alec climbed back down to the cargo deck and went to their Sno cars. On the ground, the ramp came down and they drove out of the copter and across the pad towards Snow Hydrology Section's motor park. The Sno cars were parked in the garage for a service check and with their ruckpacs slung over one shoulder, they headed for the offices.

The prominent peak of Mount Spokane north of the city gleamed intermittently as the sun began to break through the remnants of the storm now blowing away to the east.

"I hope I don't get transferred out of the Region," Alec said moodily as he surveyed the distant mountain.

"Why should you?" Troy asked.

"You never know what's going to happen when you step up a notch," Alec replied. "You know that both of us are due for grade promotion sometime this year to senior status. Depends on how many Grade One senior hydrologists they need in the Region."

"Snow is snow," Troy shrugged. "It doesn't really make that much difference to me. If they want me to move, I'll move."

"It's doesn't make much difference to you," his partner said, "because you're not married yet. But with Carol and Jimmy, it makes a lot of difference to me. It's bad enough living like we do here, jamming in against five hundred other families in the complex. The only thing that makes it worthwhile is the chance to get away from the city with the family on our days off. I want that kid of mine to know what real country looks and feels like. G.o.d help him if I should get transferred back east."

"You could always resign," Troy said half seriously.

Alec stopped dead in his tracks and turned to stare at him. "Are you out of your mind," he cried. "Resign from this for what? For the chance to be buried in a city or a bureau for the rest of my life?

Never to see the mountains except on rare vacations and then with a guide on my back? Never to see a river flowing or fight a trout? Have my kid grow up with his only knowledge of the woods from history books with an occasional trip to the zoo to see what a deer or elk looks like. I'd rather half-starve as an autologger operator in some gyppo timber camp than live like that."

"I was just kidding," Troy said. "When it comes right down to it, I wouldn't be happy away from this either. Come on, let's check in with the 'Scourge of the Northwest.'"

At SHS headquarters, they dropped their ruckpacs by the door and Alec fished the faulty radiation gauge from his pack. Then they went in to report to Snow Supervisor Morley Wilson, known affectionately to his subordinates as "The Scourge."

The leather-textured face of the senior engineer turned up at them as they entered the office. Wilson's face was tanned and weather-beaten by the sun, wind and snows of a thousand mountains and it was rumoured that when he went up for annual physical examination, the lab merely ran pollution tests on the ice water that flowed in his veins instead of blood.

"I didn't expect you two back so soon," he said with a scowl. "What's the matter? Couldn't you get to the gauge?"

Alec laid the faulty device on Wildon's desk. "No trouble, boss. Just speedy work by your best juniors."

Wilson snorted. "You must have had the chopper land you on the ridge in spite of orders." He reached for the gauge. Troy and Alec exchanged smiles. The old man had received a full report of the conditions in the Sawtooths together with a check on their activities at least an hour ago. He knew what they had to contend with to switch the gauge--and he knew they knew he was just barking.

"Another one of the transmitters shot again," he muttered. Wilson punched the intercom on his desk. "Shiver," he called, "get up here and get this radiation gauge you said was so good."

In the communications repair section three levels underground, the senior comm tech snapped out a fast "yessir" and bolted for the door.

"What did you leave up there?" Wilson asked.

"We put a CS gauge thirty feet from the survey point," Troy said. "It was working fine and it's on a flat shelf with virtually the same pack and strata formation this one came out of."

"What's it look like up there," Wilson asked. The supervisor was nearing the end of forty years of service with Snow Hydrology and in his early days, the last vestiges of the crude "man-on-the-spot"