HOW TO TELL WHEN YOU'RE TIRED: A BRIEF EXAMINATION OF WORK By Reg Theriault W.W. Norton & Co., 188 pp., $18 As longshoreman Reg Theriault is quick to point out, few books on work have been written by people who do arduous physical labor. In a loosely strung together series of essays, Theriault gives an insider's view of what it means to earn one's daily bread through heavy exertion. Theriault's folks were fruit tramps, a derogatory term that belies the pride and considerable remuneration he found in this occupation in the immediate post World-War II years. Theriault vividly recalls his willingness to drudge under the hot Texas sun in order to pack melons for the American table. Why did he do it? Before the new varieties of melons allowed them to be picked hard and green, melon packers earned three times as much as the average skilled American worker. Toiling through 15 hour days, Theriault was able to get a year's salary in four months. Most of Theriault's working life was spent as a longshoreman on the San Francisco docks, unloading coffee, cotton, copra, and hides. After a day of tackling heaps of raw hides, a worker had no trouble securing an empty seat on the public bus for the ride home. With such foul, heavy cargo to carry, successful longshoremen quickly mastered the traditional skill of working on and off. Theriault relates how working on and off became an inveterate part of the American workplace. Basically, working on and off means taking it easy while someone else covers for you. In highly repetitive work, working on and off not only allows employees to take a break but also symbolically asserts their right to some control over their work. At heart, Reg Theriault is a pragmatist. ''Management is going to get more out of you than it gives,'' he counsels. ''This is a fact of life, and one might as well accept it.'' While he is not mean-spirited about the inevitable, neither is he complaisant. He suggests several unorthodox strategies to get management's attention to poor or burdensome working conditions. In a lifetime of labor and reflections, Theriault has observed workers' longing for a vaguely articulated freedom. He explains that those on the assembly line frequently daydream of three other fields of employment: fishing, cabinetmaking, and truck driving. From the point of view of a person who does the same job each day, each of these tasks has an enviable measure of variety and choice. Among younger blue-collar workers, Theriault sees an impatience with the older generation's ability to do dirty, monotonous, or disagreeable jobs. Self-employment schemes appeal to the young far more than they do to workers with childhood memories of the depression. Theriault's book concludes with an extended analogy between the manual laborer and the legendary Greek, Sisyphus, who was fated to push a rock uphill only to witness its eternal roll back down again. But Sisyphus, unlike Theriault, had no idea that his tedium could be relieved by automation. Theriault saw hydraulics, computers, and containerization lessen the number of Americans who work by the sweat of their brows. One has to wonder if the so-called jobless future would make Theriault - and even Sisyphus - nostalgic for their chores.