BY WALTER M. GIBB

WALTER M. GIBB is on the news staff of the Baltimore SUN and has contributed from time to time to these pages.

The wreck of my reputation occurred on a miniature railway that runs around a city park in the good old summertime. It’s called the Zoo Line, and I shouldn’t have been on it at all. As far as my eight-year-old grandson is concerned, I fear I’m guilty of a shocking lapse in grown-up behavior — and from his large accusing eyes there is no appeal.

A month or so earlier I might have gotten away with it; my small safari might even have been applauded. But children grow up overnight. To paraphrase a favorite, there comes a time in the life of every child that is known as the adult hour. It is the awful moment when childhood seems suddenly childish. The new man leans his three-foot-six against the playroom door, surveys his toystrewn past, and decides to kick the habit.

Saturday, the day of my fateful ride, I found little Mark in his room surveying the field, so to speak. He declined an invitation to play marbles. Nor did he care to work a jigsaw puzzle, assemble a truck, or complete a castle begun the day before. Then, though I do not fancy violence in the forenoon, I suggested a spot of cowboy and Indian. But, no; that was for kids, he said. So I resumed coloring one of his picture books, something I do rather well, staying always within the lines and choosing colors which are an improvement upon those found in nature. When Mark did not join me even in this, I began to suspect the extent of his Weltansicht.

It was while crayoning a particularly handsome amethyst elephant that I proposed our trip to the zoo. I wanted to see his little face light up again. He thought I wanted to see the animals.

I can remember previous outings, when my wife and I spent the time en route admonishing Mark: he mustn’t run from us in crowds, when it is easy to get lost; he mustn’t eat continuously, which would make him ill, and so on. Upon this occasion, however, the words of caution were Mark’s: we mustn’t buy him a balloon. Because, he said, he was too old for that. I confess I had rather looked forward to a balloon, but my wife, who handles diplomatic situations in our family, said, “Of course you are, dear.”

I found a parking place near the depot, which is to say, near the makebelieve depot of the park’s miniature railroad. As we approached, the concessionaire was doing some highly provocative train calling, and the coaches were already filling up, for the most part with small children. I stopped, fascinated. “How about it?” I asked, already reaching for the fare. But Grandson Mark, doubtless dissuaded by the extreme youth of the boarding passengers, shook his head, and my wife signaled me on.

The situation recalled an incident of two summers past, when I had put Mark on a merry-go-round in Chicago’s Lincoln Park. While waiting for him, I’d noticed a small boy standing beside me also watching the carrousel, rather wistfully I felt, and I had asked if he wanted to ride. “Oh, no, sir,” he replied politely; “I get dizzy.” Then he pointed to a man careening around on a painted horse. “That’s my daddy,” he said. “He never gets dizzy.” That had provoked a mild sense of outrage, but today, as the three of us marched off toward the lions’ den, my feelings about the grown-up merry-gorounder softened considerably.

Mark, however, having vetoed the zoo’s train, seemed equally apathetic about its animals, although I did my best for them, too. At the camel enclosure, for example, I related how the Wise Men had ridden to Bethlehem on ancestors of that very animal. And didn’t that make it a singular privilege for us to be able to gaze upon this one now? “I seen him a hunnert times,” Mark said.

“Well, not quite,” I began, but the little train went by just then, effectively drowning my remonstrance. Above the clamor of its locomotive we could hear the engineer announcing: On our left . . . Cleopatra, the zoo’s oldest camel. . . .” My wife put her hands to her ears. As for me, I stood beside old Cleo in the burning sand, one hand clutching my burnous, the other saluting this passage of the Orient Express.

Minutes later the train went by us again, this time near the buffalo compound, and again I watched it out of sight. “Come along,” my wife said at last. “They wouldn’t let you run it anyway.” And Mark said, “Can we have a Coke?”

We had them at the refreshment stand, which is on a hill beside the bird sanctuary. From there I could see down to where our car was parked near the miniature railway station. Strictly speaking, the Zoo Line is not a railway, for there are no rails. The locomotive, which is a replica of the modern diesel, runs on concealed tractor treads and pulls its string of coaches along marked sections of the walk and roadway.

“I think that while you’re sitting here,” I said, “I’ll just run down to the car and lower the windows, so it won’t be like an oven when we get in. OK?”

“OK, Grandaddy.”

“And, dear,” my wife began.

“Yes?”

“Don’t do anything foolish, will you?”

I laughed. I knew what she meant. At times, when going off by myself like that, in amusement parks especially, I have kind of thrown my weight around, buying little surprises for everybody — pennant canes, spun candy, cupid dolls, that sort of thing. Once last summer I brought back a jump rope for my wife, which for some reason made her cry. So now I held up three fingers: “No stuffed animals, I promise.” And I hurried on down.

That had been a good thought, about the car windows, and I actually did go and lower them, but what I’d really wanted was to see the miniature train come in. I’m not what you would call a railroad buff, the sort who walks around his Christmas garden in striped overalls and gauntlets carrying a gooseneck oil can, but I do have a thing about trains, and this one got me. Since it went nowhere special, stopping where it had started, it imposed no limits upon the imagination; it was pure essence of train. And it was too much for me. I was carried away —quite literally, as it happened. And I hadn’t meant to be. I swear I hadn’t.

I stood in the small depot and watched the fascinating thing round its last curve behind the tiger cages and roll home. I waved at the engineer, exactly as I had waved to him years ago on the Illinois prairie, and he waved back. And when the train stopped I found myself scanning the faces of departing passengers for any I might know — perhaps an aunt or uncle from some far-off place, who would first laugh, and then cry, and declare I hadn’t changed a whit in forty years. But there was no such. And when the stationmaster approached with my ticket in his hand, I paid him as a matter of course and got on just as the diesel horn began to sound. Next thing I knew we were rolling out of the depot, while many whom I could not name stood waving good-bye.

That’s the way it was. I should like to be able to say that I had weighed the issue and decided to go because it was a short ride after all, one from which I would return almost before I was missed, and so on, but I can’t. Because it wasn’t so. The simple truth—or awful, depending upon your point of view — is that not until we had reached the rock pile of the aoudads, which is about halfway, did I become aware even of the commentary which the engineer kept up over the train’s public-address system. And it was not until the bird sanctuary came into view that I remembered the folk I had left behind me. For that matter, I soon saw that they were no longer behind in a spatial sense; they were practically dead ahead, for the Zoo Line rightof-way skirted the refreshment stand. And it was only a matter of seconds before we were careening by at a breathtaking four miles an hour. I waved, tourist fashion, and my wife waved back, a bit casually I thought, considering. But Mark — Mark just stared.

About live minutes and countless miles later, with a big to-do of horn blowing, the diminutive diesel pulled into its depot. And this time, I rejoice to say, there were relatives on hand to meet me. One was the woman I had married back in the States, who said only that we had better hurry home now, for I must be almost starved after that journey. The other was my grandson, who may even have forgotten what I looked like, since he peered at me rather strangely and said nothing, nothing at all.