Walt shook his head. "The easy part," he said uncheerfully. "By which you mean the manner in which we contact them and make them listen to us?" "That's her," said Don with a cheerful smile. "Fine," said Thomas. "Now what do we do?" "Clear up this mess so we can make the cam. This drawing will do, just grab the tablecloth." Joe, the operator of Venus Equilateral's one and only establishment for the benefit of the stomach, came up as the three men began to move their glasses and dishes over to an empty table. "What makes with the tablecloth?" he asked. "Want a piece of carbon paper and another tablecloth?" "No," said Don nonchalantly. "This single copy will do." "We lose lots of tablecloths that way," said Joe. "It's tough, running a restaurant on Venus Equilateral. I tried using paper ones once, but that didn't work. I had 'em printed but when the solar system was on 'em, you fellows drew schematic diagrams for a new coupler circuit. I put all kinds of radio circuits on them, and the gang drew plans for antenna arrays. I gave up and put pads of paper on each table, and the boys used them to make folded paper airplanes and they shot them all over the place. Why don't you guys grow up?" "Cheer up, Joe. But if this tablecloth won't run through the blueprint machine, we'll squawk!" Joe looked downcast, and Franks hurried to explain: "It isn't that bad, Joe. We won't try it. We just want to have these figures so we won't have to run through the math again. We'll return the cloth." "Yeah," said Joe at their retreating figures. "And for the rest of its usefulness it will be full of curves, drawings, and a complete set of astrogating equations." He shrugged his shoulders and went for a new tablecloth. Don, Walt and Chuck took their improvised drawing to the machine shop, where they put it in the hands of the master mechanic. "This thing has a top requirement," Don told him. "Make it as quick as you can." Master Mechanic Warren 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 for 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."