JUDGING FROM THE SPATE of new books on the subject, good old-fashioned walking is hard on the heels of jogging as a mass exercise. For Americans, pushed to ennui by industrial conurbation and the inanity of popular entertainment, it's a welcome development.

Walking is superior to jogging on several counts. Though it takes a bit more time, overall it is better exercise. Quite as important, unlike jogging, walking admits change. In walking, you can compose a poem (Wordsworth wrote most of his while walking more than 150,000 miles!), whistle or sing a song, or smile (when last did you see a similing jogger!). Or you can stop. Then "as you sit on the hillside, or lie prone under the trees of the forest, or sprawl wet-legged on the shingly beach of a mountain stream, the great door, that does not look like a door, opens," as Stephen Graham wrote in his classic The Gentle Art of Tramping (1926).

"Gait" describes the carriage, rhythm, and speed used. It can take many forms - from the mosey through the 3 mph most of us use, and the 4 mph traditionally used by the military, to the 8 mph of the race walkers - faster than most joggers run. Motives, which are many, determine gait. Walking can be a bird-watching amble or it can be aerobic, which means, an anti-exercise friend tells me, that you will die in better shape than more sedentary types. But your gait and motive don't matter in the deomcracy of walking. According to the historian, G. M. Trevelyan, "it is a land of many paths and no-paths, where every one goes his own way and is right."

Most of the great men of yore were walkers. Aristotle even called his school of strolling thinkers the Peripatetics (335 B.C.). The Greeks did it thinking and the Roman legions marched 21 miles a day warring. And, God knows, Christ walked. In our time, Harry Truman's two miles per day would have amused R. L. Stevenson who thought 25 miles was the least one should walk. Threau had to have four hours of it daily to "get rid of the rust I had acquired." And Bach hiked 200 miles once to hear the famed Buxtehude play the organ.

But the British were the best at the pastime. Men walked 20 miles to a dinner party. Lame Walter Scott walked 30 miles; Coleridge and De Quincey while on opium could get up to 40 miles. The best he's ever done, Carlyle said almost sadly, was 54 miles. America's greatest walker was perhaps Edward Weston who at 70 walked from San Francisco to New York City in 104 days - an average of 37 miles a day. But my favorite is George Johnson who in 1926 walked 578 miles in 20 while fasting.

Here is a small knapsack of new books on walking and not a bad one in the lot. John Man's Walk! is slightly marred by too many pictures of himself (a gentleman is a man who can play the saxophone, but won't), but has the finest section of health and fitness factors. Most of the books provide walking programs for both sexes and all ages, and some have special regimes for heart patients and pregnant women.

Food is covered, but perhaps too amply. True, the one wants to avoid the heavy diet John Man cites (from Pat McManus' A Fine and Pleasant Misery, 1978); potatoes, onions, beans, and bread - all fried in bacon grease. "After meals, indigestion went through our camp like a sow grizzly with a toothache. During the night coyotes sat in nervous silence on surrounding hills and listened to the mournful wailing from our camp." But, some backpackers eat better on the trail with freeze-dried and other delicacies than at home. John Muir, who walked most of America, had the right idea: "I throw a loaf of bread and a pound of tea in an old sack and jump over the back fence."

Much space is also given to garb, shoes especially, and two of the books - Kuntzleman's and Gale's - detail walks in American cities. This is needed. But they fail to mention the dangers of breathing polluted air (I am still puzzled by joggers hyperventilating along roads inspissated with auto fumes) or to sound a cautionary note on muggers who often go down the same mean streets. If you can get out of town, Ed Garvey's book will take you for the more wholesome and safe hiking done on the Appalachian Trail stretching 2,000 miles between Georgia and Maine.

Donald Peattie, the naturalist, learned how to walk from a master who taught him to climb without getting winded - slanting his body forward on the balls of his feet; never to take a highroad if he could find a bypath; to quench his thirst before starting; and to go stoutly shod and lightly clad. These four books can't teach you to walk, but they will teach you much about the vertical act, as well as stimulate and sustain many walks. CAPTION: llustrations, from "The Walking Book," by Gerald Donaldson (Holt, Rinehart and Winston)