Master Mechanic Walton took the cloth and said: "You forgot the note. You know, 'Work to dimensions shown, do not scale this drawing.' Lord, Don, this silly-looking cam will take a man about six hours to do. It'll have to be right on the button all over, no tolerance. I'll have to cut it to the 'T' and then lap it smooth with polishing compound. Then what'll you test it on?" "Sodium light interferometer. Can you do it in four hours?" "If nothing goes wrong. Brass all right?" "Anything you say. It'll only be used once. Anything of sufficient hardness to withstand a single usage will do." "I'll use brass then. Or free-cutting steel may be better. If you make it soft you have the chance of cutting too much off with your lapping compound. We'll take care of it, Don. The rest of this stuff isn't too hard. Your framework and so on can be whittled out and pasted together from standard girders, right?" "Sure. Plaster them together any way you can. And we don't want them painted. As long as she works, phooey to the looks." "Fine," said Walton. "I'll have the business installed in the Beam Control Room in nine hours. Complete and ready to work." "That nine hours is a minimum?" "Absolutely. After we cut and polish that screwball cam, we'll have to check it, and then you'll have to check it. Then the silly thing will have to be installed and its concentricity must be checked to the last wave length of cadmium light. That'll take us a couple of hours, I bet. The rest of the works will be ready, checked, and waiting for the ding-busted cam." "Yeah," agreed Franks. "Then we'll have to get up there with our works and put the electricals on the mechanicals. My guess, Don, is a good, healthy twelve hours before we can begin to squirt our signal." * * * * * Twelve hours is not much in the life of a man; it is less in the life of a planet. The Terran standard of gravity is so small that it is expressed in feet per second. But when the two are coupled together as a measure of travel, and the standard Terran gee is applied for twelve hours steady, it builds up to almost three hundred miles per second, and by the end of that twelve hours, six million miles have fled into the past. Now take a look at Mars. It is a small, red mite in the sky, its diameter some four thousand miles. Sol is eight hundred thousand miles in diameter. Six million miles from Mars, then, can be crudely expressed by visualizing a point eight times the diameter of the Sun away from Mars, and you have the distance that the _Empress of Kolain_ had come from Mars. But the ship was heading in at an angle, and the six million miles did not subtend the above arc. From Venus Equilateral, the position of the _Empress of Kolain_ was more like two diameters of the Sun from Mars, slightly to the north and on the side away from Sol.