The Cambridge, Mass., Rescue Squad is not typical of other such companies in the States, since it provides a unique combination of fire, rescue and emergency medical service. It operates out of Harvard Square and attends every emergency in the city, last year making nearly 4700 runs. It's staffed by a mere four squads of five members each and Larry Ferazani is one of them, working a rotation schedule of ten-hour days and fourteen-hour nights. Volunteers all, these young men last about five years; by then the pressure of constant exposure to death and public horror is so great that transfer is necessary. Despite their spirit-breaking jobs, these rescuers have a sense of fulfilling personal reward: Ferazani says, "". . . for the first time in my life I have a calling which gives me deep satisfaction."" He has an admittedly eccentric view of life in Cambridge but it is a legitimate, vast unease based upon the terror of human waste from alcoholism, suicide, madness in one of the country's favorite cities. A terrific inside story.