But Professor Eddinger, a cog in the wheels of a great educational machine, glanced at the watch on his wrist. Again his thin shoulders were stooped, his voice tired. "My classes," he said. "I must be going...." * * * * * In the gathering dusk Professor Eddinger locked carefully the door of his office. He crossed beyond his desk and fumbled with his one hand for his keys. There was a cabinet to be opened, and he stared long in the dim light at the object he withdrew. He looked approvingly at the exquisite workmanship of an instrument where a generator of the cathode ray and an intricate maze of tubing surmounted electro-magnets and a round lead bulb. There were terminals for attaching heavy cables; it was a beautiful thing.... His useless arm moved to bring an imaginary hand before the window of quartz in the lead sphere. "Power," he whispered and repeated Avery's words; "power, to build a city--or destroy a civilization ... and I hold it in one hand." He replaced the apparatus in the safety of its case. "The saviors of mankind!" he said, and his tone was harsh and bitter. But a smile, whimsical, kindly, crinkled his tired eyes as he turned to his desk and its usual litter of examination papers. "It is something, Avery," he whispered to that distant man, "to belong in so distinguished a group." A STAR THAT BREATHES Beta Cephei, the mysterious Milky Way star which expands and contracts as though it were breathing, at last has a biography. A summary of known facts concerning the star, interpreted in the light of recent observations at the Lick Observatory at the University of California was completed recently by H. S. Mendenhall, graduate student. Mendenhall's interpretations were said to lend weight to the theory that Beta Cephei is contracting and expanding once in every four and one-half hours. This is such a terrific rate of speed from a terrestrial point of view that it appears to be moving toward and away from the earth at a velocity reaching a maximum of about nine and one-half miles per second. Beta Cephei is a variable star in the Constellation Cepheus. It is best visible in the northern sky during July or August. Its distance from the earth is estimated roughly at 2,000,000,000,000,000 miles, and Mendenhall estimates its diameter at almost 2,000,000 miles, more than twice that of the sun. In addition to the apparent velocity caused by contraction and expansion of its surface five times a day, Beta Cephei seems to have another motion. This was said by Mendenhall to be a rotation around some other star in a period of 20 years. Velocity of this rotation is something over three miles a second.