JUST OVER 140 years ago, when New York was a mini-city of 250,000 people, and Columbia University was a mini-college with barely 100 students, a boy named George Templeton Strong graduated at the age of 18, and immediately began the study of law. At 21 he entered practice with his father's Wall Street firm. Soon he plunged headlong into the life of the city. At 27 he became a vestryman of Trinity Church, at 33 a trustee of Columbia. At 36 he helped to found the Columbia Law School; at 40 he found himself placed (to his astonishment) on an all- male committee which was to decide who was "in" society and who was out.

At 41 he all but laid aside his law practice for four years to work for the great Sanitary Commission that saved so many soldiers' lives during the Civil War. At 44 he declined the presidency of Columbia. At 50 he became president of the New York Philharmonic Society. Meanwhile, he had married and raised a family, been to almost every fire in the city, attended all the concerts, heard all the gossip, followed all the elections, been interested in pretty much everything that happened in this country in his time.

He had meanwhile kept a 4-million-word diary. It begins when he is 15, and ends only with his death in 1875. It is full of nuggets, delights and gems. Through it one can track the growth of all sorts of things in America. Technology, for example. The industrial revolution took shape in his time, and Strong followed it with fascination. Back in 1836, when he was only 16, an older relative took him on board one of the big new steamboats then beginning to appear in eastern ports. "She is a superb boat, and has baths on board, which is quite a novel arrangement," he wrote admiringly in his diary.

He watched the growth of factories--and aristocrat though he was, felt furious most of his life at the working conditions in them. When a big and shoddily built one in Massachusetts collapsed, killing many of the women and girls who worked in it, Strong quite seriously would have liked to see the owner hanged. "Somebody has murdered about two hundred people, many of them with hideous torture, in order to save money, but society has no gibbet for the respectable millionaire."

He rode on the new railroads, admired a piece of the new metal called aluminium that a friend showed him, cast his vote in one of the new glass ballot boxes that were part of the (vain) attempt to reform city politics. ("They say the price of a councilman is from $10 to $25," he noted angrily on December 29, 1854. He means, of course, for a vote on any one particular bill. Even then, it cost a lot more to buy one full-time.) And all these things he recorded.

That's only the public side of his diary. Ample as that is, it pales before the private side. Strong gives a really stunning evocation of what it was like to be a city dweller back in the days of our national innocence. It was rather different than most people imagine. For example, it was less quiet than I had supposed. Probably from a series of English movies, and maybe a few Currier & Ives prints, I had thought 19th-century city sounds were mostly the clip-clop of horses' hooves, and a few picturesque street-sellers' cries. Not so. Here is an entry Strong made on June 15, 1845. He was living in his father's big brick house on Greenwich Street.

"This being Sunday night, our neighbors in the rear are comparatively quiet--there's only the average choir of cats, a pulmonary horse (stabled within 25 feet of this room), afflicted with a periodic cough of great severity at regular intervals of about 15 minutes, and a few drunken Dutch emigrants singing what I've no doubt's a highly indecent Low Dutch canticle, fortunately unintelligblle. . . . It's quite a Sabbath stillness; for an ordinary evening, there are two Dutch lust-houses in Washington Street that keep an orchestra apiece. . . ."

Some stillness.

Or he'll note in 1857 that there's such a crime wave that most of his friends have bought revolvers, and carry them. (A gang called the Dead Rabbits was behind a lot of the trouble.) And he decides that if he had to be out on foot after dark much, he'd do the same, "though it's a very bad practice carrying concealed weapons."

More personally still, you learn of Strong's numerous experiments with drugs. He doesn't take opium, though there was plenty in the city ("much more than people think"); it was that new drug chloroform that he loved to trip with. "It seems an innocent kind of amusement, not followed by any reaction or other unpleasant symptoms," he coolly writes when he is 28--and then records his latest trip in full detail. (Among other things, he hallucinated a performance of Mozart's Requiem, with "accompaniment by an orchestra and, as I noticed at the time, not a very good one.") Eight years later he is still enjoying periodic chloroform binges.

Most personal of all, you get his feelings as he meets, courts, and marries Miss Ellen Ruggles. There is an especially touching dialogue he holds with himself two weeks before the wedding.

His romantic self says to him that he's going to worship her forever. His commonsensical self presumes to doubt. "Don't you know that five years hence or ten years hence your Wife will be an everyday affair and not the lovely novelty she is now?" And he makes himself a solemn promise never to act as if she were everyday. (He mostly kept it, too.)

But there is really a record of almost everything in this book. You want to know when flowers began commonly to appear on altars in Protestant churches in New York? In 1856. "Censured as papistical, of course." Want to know the state of mathematics in American colleges five generations ago? Well, granted that Columbia happened to be in especially bad shape, scientifically, in the 1850s, here's something of an eye-opener. The physics professor had complained that the math professor was incompetent (true), and that students were coming to him unprepared. Strong, that master of detail, records some of the problems Columbia juniors couldn't handle in 1857. They couldn't compute the interest on $1,000 for 60 days at 7%; they couldn't say how much 3/4 of 5/5 came to; they couldn't prove the Pythagorean theorem. Educational standards in 1981 may be less disastrous than people fear.

Strong already had a solution in mind, incidentally, for keeping professors on their toes. He'd heard it from Professor Peirce of Harvard. You should just require them "to accomplish something every year or every six months . . . some essay, memoir, or investigation."

Just so I won't seem to be picking on Columbia, want to know how Yale struck an elegant New Yorker in 1846? As piddling and provincial. After sneering at the buildings, Strong notes the social life of the faculty. He went to "Mrs. Salisbury's big dinner party--very magnificent affair--no wine."

Strong also records hundreds of cultural events, and here the note is usually one of joy. Our symphonic warhorses were to him contemporary music. He particularly loved what we call Beethoven's Fifth and he called the C Minor Symphony. The Strongs heard a performance on September 29, 1853. "That noblest of compositions was never so played in this city before. Ellie was cured of a cold by it."

There are some less pleasing entries, of course. Like most people of his time and class, Strong was a good deal of a bigot. He didn't think much of Irish immigrants, and he thought even less of blacks. (Though his slow and reluctant conversion to anti-slavery feeling will make a fascinating case study. The first glimmerings appear in 1854. Actual dawn was in 1856, when Rep. Preston Brooks of South Carolina clubbed Sen. Charles Sumner of Massachusetts in the Senate chamber, for speaking too virulently against slavery. "The reckless insolent brutality of our Southern aristocrats may drive me into abolitionism yet," Strong wrote. By 1860 he was voting for Lincoln.)

In any case, Strong's sharp tongue was by no means reserved for blacks and immigrants. He could be devastating on his fellow WASPs. Here is his description of that reverend old gentleman Peter Cooper, founder of the Cooper Union. The Prince of Wales is visiting New York; Strong is on the committee to receive him. He is watching his fellow New Yorkers surge in to the reception, eager to clasp the hand of royalty. Among those who catch his attention are "old Pelatiah Perit (who looked like a duke in his dress coat and white cravat) and Peter Cooper, who looked like one of Gulliver's Yahoos caught and cleaned and dressed up."

Or consider what he had to say about John Tyler at a time when that gentleman was 54 years old and president of the United States. (Strong is 24.) He has just heard that the president has married again--"one of those large fleshy Miss Gardiners of Gardiner's Island." Strong does not respectfully salute the chief magistrate, and wish him felicitations. "Poor, unfortunate, deluded old jackass," he writes. "It's positively painful to think of his situation, and the trials that lie before him." The fact is that most good diarists have a touch of acerbity.

The great ones--and Strong is of their number--have something more. Or, to be accurate, one of two things. They have either a self-absorption so intense and so pure that it transcends both self and selfishness. Anne Frank is an example. Or they have an inexhaustible love of the world they live in. Pepys is of this kind. So is George Templeton Strong. In 1855, a few months before Whitman brought out the first obscure edition of Leaves of Grass, Strong made an entry which expresses that embracing love. It is worth quoting at length. He has been thinking about American poets, and wishing they would leave the Middle Ages and Helen of Troy alone. Let them look homeward.

"There is poetry enough latent in the South Street merchant and the Wall Street financier; in Stewart's snobby clerk chaffering over ribbons and laces; in the omnibus driver that conveys them all . . . in the sumptuous star courtesan of Mercer Street thinking sadly of her village home; in the Fifth Avenue ballroom; in the Grace Church contrast of eternal vanity and new bonnets; in the dancers at Lewis Jones and Mr. Schiff's, and in the future of each and all."

Nice words, those. Strong is, in fact, a kind of upper- class Whitman--a fact he almost certainly didn't know, since he seems never to have read or met Walt.

There is one last thing to add. Quoting especially good passages as I have been, I may have given the impression that the whole four volumes of this diary are worth reading. They aren't. At least not word for word. The first few years are the precocious pedantic writing of a book- mad youth. It is only in his middle twenties that Strong really finds his style. And even after that, there is more about the politics of the Episcopal Church and the doings of Columbia College than most people are going to want to hear. But every page of the whole 2,000 is worth skimming, and there are long sections that deserve full attention.

As usual, Strong himself has the last word. He possessed a lively sense of futurity. (He loved to imagine what New York would be like a hundred or even a thousand years after his time.) Once as a young man, he imagined his descendants in the far-off 20th century thumbing through the diary. They would find it, he decided, "a queer old journal . . . that nobody could read through, but which contains curious illustrations of old times."

Curious, wonderful, and intensely real.

Note on availability: Only one edition of the diary is currently for sale--a $90. Charles reprint by Octagon Books. But most good libraries possess the original 1952 edition.