Thirty years of the ""Louisiana hayride"" given the full treatment for those who wanted to learn more than Opotowsky's The Longs of Louisiana (Dutton) gave them. But from this reader's viewpoint, the additional minutiae provide unnecessary trimming of the lily. We've had enough. (And so, we imagine, has Louisiana). It is hard luck, however, that two such superior books on the subject should come out so close together. Mr. Martin has, perhaps, a closer view of the scene as SW Bureau Chief for Time-Life at the time of the recent Earl Long uproar. He has had access to new material, which fills in some of the gaps in earlier handling of the whole incredible story of the making of a dictatorship in these United States. He has brought it up to the minute plus giving a certain objectivity of recognition to what both Huey Long and Earl Long achieved, even at a terrific cost. The New Orleans Ring before them was not an unmixed blessing, for any except the already privileged. The subservience demanded- under threat and fear- by the Long dynasty-virtually eliminated any democratic procedure and made of the state a family-owned corporation. Aspirations for the White House -- with a vote-getting Share the Wealth program -- were not to be laughed aside. Scandals and clean-ups have been well aired, competently launched, and gradually allowed to drift off, until the state was ready for the second round with Earl Long. And today- there is still a Long in the Senate, and a Long who has his eye on succession to Louisiana's governor's seat. Meantime, welfarism- not too far from the Long pattern- is in the national picture. Dictatorship- Long styled- is outmoded. But this massively detailed story of what happened should serve as a permanent finger of warning.