Sunday afternoon the visitors, presumably softened up by what one of the chemists thought were martinis, were seated in the lecture hall listening to Dr. Morton's concluding remarks.

"One of the technicians is working on a gadget with a photocell that closes the shutter on the film when a rocket goes up," Dr. Morton was saying. "It should cut down the exposure time a great deal. Right now, every night may be significant. If the plates from any one night are spoiled, we may not be able to duplicate them for a Martian year. Mankind is preparing the first trip to another star, and the work of M............