Far-future tale from the Australia author of The Centurion’s Empire (1998). By 3931 a.d., a low-tech Australian civilization is dominated by the great library at Rochester, the only city that’s free of the Call, a mysterious psychic compulsion that intermittently sweeps across the countryside, gathering all people and animals not securely tethered; those who are affected trek mindlessly to the south and are never seen again. One of the dwellers here, the dynamic and innovative chief librarian, Zarvora Cybeline, has fought many duels to defend her progressive ideas—but her greatest secret is the Calculor, a huge computer composed of an abacus array mechanically linked to human operators and controls. With the Calculor, she painlessly raises revenues by exposing embezzlers and tax cheats (they’re inducted into the Calculor), decodes the secret messages the nobles use to conceal their plotting, and improves the efficiency of the beamflash signal-tower network by which information is exchanged. Zarvora effectively rules the confederacy, though nobody has yet grasped that fact. There is, however, an urgent problem: machines working on the Moon are building a huge mirror-band that, once placed to girdle the Earth, will reflect heat away from the planet. Programmed centuries ago, the system was designed to ameliorate global warming. But the planet is no longer too warm, and the reflector, now nearing completion, would precipitate another Greatwinter like the one that destroyed the previous civilization. Among Zarvora’s other concerns: contact with people who can resist the Call; treachery; war; and further revelations about her people and her world. A stunning idea—the Calculor’s as real as if McMullen had built it in his backyard—with an utterly convincing setting, breathtaking developments, and a captivating narrative.