Observer"" columns from Russell Baker are the perfect light-beer chasers for the hard-stuff of daily news--but few of the short pieces in this pleasant, bland collection stand up well to the sterner tests of time and hard-cover compilation. The most obvious sufferers from the format, of course, are dated columns on the political scene--lots on Watergate--that are usually common-sensical enough (""this suggestion of men enacting boyish fantasies is worse than whatever crimes may have been committed. . .""), yet often over-simplified and a bit preachy. But other pieces that should be less frayed by time--on inflation, language (the ""Have a nice day"" craze), the sexual revolution, city living (parking, cabs, noise), marriage, parenthood, taxes--also tend to seem rather limp in retrospect: Baker can get cheaply sentimental (""Old people at the supermarket are being crushed and nobody is even screaming""); he often runs the risk of registering only as a less-funny Erma Bombeck (supermarket lines, washing machines). And, when consciously emulating Mencken or Perelman or Woody Allen, he consistently lacks the edge needed for that darker brand of humor. Still, none of these never-too-long pieces is without a smile or two, especially for those partial to wistful looks back to cleaner, simpler times. And in certain areas, Baker is superb: TV commercials bring out his cleanest swipes; historical whimsies inspire him to glorious flights of anachronism; and one column here is bona fide classic--""Cooped Up,"" in which the ghost of Gary C. accompanies Baker to movies that have junked all the old Coop-movie values. Less impressive the second time around, then--but Baker fans and others will find it literate, gently amusing bedside reading that's smoothly mainstream all the way.