arating the operations room from the laboratory。 A stepstool rested beside the polywater tank。
The contrivance looked as if it had been pieced together in a one…man machine shop on the backlot。
Chaney asked： 〃That thing works？〃
〃Most assuredly；〃 Seabrooke replied。
Chaney stepped over the cables and walked around the vehicle； following the invitation of an engineer。 The clock and the calendar were securely fastened to a nearby wall； each protected by a clear plastic bubble。 Above them…like perched and hovering vultures…were two small television cameras looking down on the basement room。 A metal locker； placed near the door and securely fastened to the wall； was meant to contain their clothing。 Light fixtures recessed in a high ceiling bathed the room in a cold； brilliant light。 The room itself seemed chilly and strangely dry for a basement； it held a sharp smell that might be ozone； together with an unpleasant taste of disturbed dust。
Chaney put the flat of his hand against the aluminum hull and found it cold。 There was a minute discharge of static electricity against his palm。
He asked： 〃How did the monkeys run it？〃
〃They didn't； of course；〃 the engineer retorted with annoyance。 （Perhaps he lacked a sense of humor。） 〃This vehicle is designed for dual operation； Mr。 Chaney。 All the tests were launched from the lab； as you will be on the out…stage of the journey。 We will kick you forward。〃
Chaney searched that last for a double meaning。
The engineer said： 〃When the vehicle is programmed for remote； it can be literally kicked to or away from its target date by depressing the kickbar beneath your feet。 We will launch you forward； but you will effect your own return when the mission is pleted。 We recall only in an emergency。〃
〃I suppose it will wait up there for us？〃
〃It will wait there for you。 After arrival on target the vehicle will lock on point and remain there until it is released； by you or by us。 The vehicle cannot move until propelled by an electrical thrust and that thrust must be continuous。 The tachyon generators provide the thrust against a deflecting screen which provides the momentum。 The TDV operates in an artificially created vacuum which precedes the vehicle by one millisecond； in effect creating its own time path。 Am I making myself clear？
Chaney said： 〃No。〃
The engineer seemed pained。 〃Perhaps you should read a good book on tachyon deflector systems。〃
〃Perhaps。 Where will I find one？〃
〃You won't。 They haven't been written。〃
〃But it all sounds like perpetual motion。〃
〃It isn't； believe me。 This baby eats power。〃
〃I suppose you need that nuclear reactor？〃
〃All of it…it serves this lab alone。〃
Chaney revealed his surprise。 〃It doesn't serve the station outside？ How much does it take to kick this thing into the future？〃
〃The vehicle requires five hundred thousand kilos per launch。〃
Chaney and Arthur Saltus whistled in unison。 Chaney said： 〃Is that power house protected？ What about wiring？ Transformers？ Electrical systems are vulnerable to about everything： sleet storms； drunken drivers ramming poles； outages； one thing after another。〃
〃Our reactor is set in concrete； Mr。 Chaney。 Our conduits are underground。 Our equipment is rated for at least twenty years continuous service。〃 A wave of the hand to indicate superior judgment； superior knowledge。 〃You needn't concern yourself； our future planning is plete。 There will be power to spare for the next five hundred years； if need be。 The power will be available for any launch and return。〃
Brian Chaney was skeptical。 〃Will cables and transformers last five hundred years？〃
Again the quick annoyance。 〃We don't expect them to。 All equipment will be replaced each twenty or twenty…five years according to a prearranged schedule。 This is a pletely planned operating system。〃
Chaney kicked at the concrete tank and hurt his toe。 〃Maybe the tank will leak。〃
〃Polywater doesn't leak。 It has the consistency of thin grease； and is suspended in capillary tubes。 This is ninety…nine percent of the world's supply right here。〃 He followed Chaney's lead and kicked the tank。 〃No leak。〃
〃What does the TDV push against？ That polywater？〃
The engineer looked at him as if he were an idiot。 〃It floats on the polywater； Mr。 Chaney。 I said the thrust against a screen； a molybdenum screen provides the momentum to displace temporal strata。〃
Chaney said： 〃Ah！ I see it now。〃
〃I don't；〃 Arthur Saltus said mournfully。 He stood at the nose of the vehicle with his nose pressed against the transparent bubble。 〃What guides this thing？ I don't see a tiller or a wheel。〃
The engineer gave the impression of wanting to leave the room； of wanting to hand over the instruction tour to some underling。 〃The vehicle is guided by a mercury proton gyroscope； Mr。 Saltus。〃 He pointed past the mander's nose to a metal cube within the bubble； nestled alongside the camera。 〃That instrument。 We borrowed the technique from the Navy； from their program to guide interplanetary ships in long…flight。〃
Arthur Saltus seemed impressed。 〃Good； eh？〃
〃Superior。 Gyroscopes employing mercury protons are not affected by motion； shock； vibrations； or upset； they will operate through any violence short of destruction。 That unit will take you there and bring you back to within sixty…one seconds of your launch。 Rely on it。〃
Saltus said： 〃How？〃 and Major Moresby seconded him。 〃Explain it； please。 I am interested。〃
The engineer looked on Moresby as the only partly intelligent non…engineer in the room。 〃Sensing cells in the unit will relay back to us a continuous signal indicating your time path； Mr。 Moresby。 It will signal any deviation from a true line； if the vehicle wavers we will know it immediately。 Our puter will interpret and correct immediately。 The puter will send forward the proper corrective signals to the tachyon deflector system and restore the vehicle to its right time path； all in less than a second。 You will not be aware of the deviation or the correction； of course。〃
Saltus： 〃Do you guarantee we'll hit the target？〃
〃Within four minutes of the annual hour； Mr。 Saltus。 This system does not permit a tracking error greater than plus or minus four minutes per year。 That is on target。 The Soviet couldn't do any better。〃
Chaney was startled。 〃Do they have one？〃
〃No；〃 Gilbert Scabrooke interposed。 〃That was a figure of speech。 We all have pride in our work。〃
Seniority was all。 Major Moresby made the first trial test； and then mander Saltus。
When his turn came； Chaney undressed and stored his clothing in the locker。 The hovering presence of the engineer didn't bother him but the prying eyes of the two television cameras did。 He couldn't know who was on the other side of the wall； watching him。 Wearing only his shorts…the one belated concession to modesty…and standing in his bare feet on the concrete floor； Chaney fought away the impulse to bolster his waning ego by thumbing his nose at the inquisitive cameras。 Gilbert Scabrooke probably wouldn't approve。
Following instructions； he climbed into the TDV。
Chaney wriggled through the hatch； lowered himself onto the sling…like bed； and promptly banged his head against the camera mounted inside the bubble。 It hurt。
〃Damn it！〃
The engineer said reprovingly： 〃Please be more careful of the camera； Mr。 Chaney。〃
〃You could hang that thing outside the bucket。〃
Inching lower onto the flimsy bed； he discovered that when his feet reached the kickbar there was insufficient room to turn his head without striking either the camera or the gyroscope； nor could he push out his elbows。 He squinted up at the engineer in protest but the man's face disappeared from the opening as the hatch was slammed shut。 Chaney had a moment of panic but fought it away； the drum was no worse than a cramped tomb…and better in one small respect： the transparent bubble admitted light from the ceiling fixtures。 Still following the detailed instructions； he reached up to snug the hatch and was immediately rewarded by a blinking green bull's eye above his head。 He thought that was nice。