The great memorial to Franklin Delano Roosevelt is coming along as rapidly as anyone could hope, which means that within the lifetime of some now breathing it will be complete.

A bold guess is that the memorial will be completed four or five years from this Memorial Day, adding to the capital a special sort of garden indeed.

In essence, the memorial is a walk through a garden, broken into rooms or retreats by granite walls, and limpid pools and waterfalls and roses, with places to rest and reflect. Sculpture the Roosevelt contribution to history.

As memorial go, this one, designed by Lawrence Halprin of Associates of San Francisco, has met no great opposition and has somehow managed to pass the Fine Arts Commission, the Memorial Commission, the Parks committees and the Roosevelt Family.

Some have muttered at its probable cost of $20 million, and an occasional critic, such as Wolf Von Eckardt for The Washington Post, has mourned that we thought we re going to get rose garden as a memorial to FDR, but are gettin an "oh-so-artistic amusement Park" and it all sounds "like an awful lot, this hyperthyroid outdoor museum."

On the other hand, you have to admit that a memorial derived from the concept of a garden has at least as many possibilities as one derived from the relics of Luxor, Rome or Gen U. S. Grant.

The Washington Monument is splendid because you can send out of own teen-agers up its steps and you can see it for miles distant, and the John F. Kennedy memorial (no matter what you think it looks like) will feed you in its restaurants and divert you in its theaters.

The Lincoln and Jefferson Memorials are said to inspire reverence, awe or affection among many, and nobody would wish to tamper with the pieties of those who think the memorials are impressive.There is not much, however, to do or see at either of them.

The Roosevelt Memorial does not look at all like an Egyptian or any other temple, but it does echo, a little, those most ancient gardens of fish pools and vine arbors. Not that I have been able to find any provision for grapes on arbors (a particular enthusiasm of my own) but the general effect of walking along the water, with garden walls and verdure always in sight, is delightful.

Roses have been a thorny issue, of course. As the Memorial Commission observes, roses are "dead" for much of the year and require a lot of attention in weeding, spraying and pruning, so they cannot say how many roses there will be.

Rose bushes are also decidedly ugly, apart from their flowers, at least at commonly seen in Washington public plantings. The obvious solution to that is to use roses other than the one commonly seen - roses rich in beauty of habit, even when out of bloom, and lovely in folige and fruit. If I were doing such a memorial, I would consult with somebody who knew what was what, among roses, and would therefore wind up with Graham Stuart Thomas, a world authority. I certainly would not entrust the selection to people who have no need to know beans about the subject.

All of which illustrates a central headache of any national memorial: A vast number of skills are necessary and a great deal of experience and taste is necessary, yet a great many particular interest must be satisfied.

The stone walls, the roses meets sculptures - there is more than meets the eye here. Nobody would approve a stonewall a thousands feet long, for no purpose. And yet - when you break it up into segments and turn it at right angles here and there, and dispose open places along its length - it depends on how this is done, whether the result is a great joy to see or a great mess.

To some. like me, the arrangement of the walls is handsome and inspired. To others, they may seem pointless. The Fire Arts Commission, at least, has given final approval to the general design, though it must pass on the sculptures (when they are finally designed) amd other details.

The complexity of such as a project accounts for the endless time required to get one built. The National Capital Planning Commission, the Department of Transportation, the District Department of Highways, the Department of Highways, the Department of Health, Education and Welfare all must be consulted.

The National Environmental Protection Agency must have its input or overput - we do not want a memorial that belches gas into the air, after all.

How do people in wheelchairs get about? Many of the town's memorials were designed with no thought for tnem, but not this one. And if you are going to close a public road such as West Basin Drive for a memorial then a good bit of closeness with the Highways Department awaits you. You of tourists, and this had better be worked out with transportation authorities ahead of time, rather than after the tourists descend.

Even the sculptures take endless time. The Memorial Commission explored with museum and art people across the country the names of possible artists. The commission wants chiefly low reliefs in bronze depicting aspects of Roosevelt's life. The subjects are not even decidd yet: maybe governor of New York. Secretary of the Navy, maybe relations with the Supreme Court, maybe Social Security fights.

Sculptors will have to winnowed down from the too-large list of suggestions, then approached for talks about what is desired. Some sculptors may have other commitments, some may refuse to work unless they (not the commission) can determine what is to be shown, some may shy away from the inevitable speeches in Congress that "it looks like a bullfrog" or whatnot. Public figures usually have poor taste in sculpture but ready quips. Thus Prince Philip, viewing a Henry Moore sculpture here, said it was "the qorst case of slipped disc" he ever saw.

Cost must be estimated far more carefully thanhas yet been done. The figure of $200 million is a general figure. But nobody can yet say.

The Park Service must hold hearings once the environmental impact statement is in. Until the final plans are made. Congress cannot be expected the memorial would take two years to complete once ground is broken, assuming Congress votes the money.

When Roosevelt was alive, he once told Supreme Court Justice Felix Frankfurter that if any memorial was to be erected to his memory, "I know exactly what I should like it to be . . . a block about the size of this (touching his desk) placed in the center that green plot in front of the Archieves Building . . ."

Such a memorial is now in place. But of course it made no difference what Roosevelt wanted, since everyone has felt free to proceed along with something quite different from "a block about the size of this." Jefferson also left specific instructions for his memorial tombstone, which was followed, but which did not rule out, apparently, the great pile of stone in honor of him at the Tidal Basin.

Congress voted in 1955 to go ahead with another Roosevelt Memorial, and the Memorial Commision was establish the next year with members appointed by the House Speaker and Senate President and the President.

Over the yers since then, competitions have been held and winners announced. Until this garden concept finally was put forward, the earlier designs were thrown out by the Fine Arts Commission as being not quite right, in the view. one was widely dubbed "Instant Stonehenge."

Assuming the various agencies (or their hearings) arouse no furious storms for the memorial, there remains the problem of getting Congress to approve the cost.

Surely there will be some high rhetoric about why a garden will costs $20 million, and somebody will probably insits there are not enough marigolds or wonder why there is not a live buffalo from the great state of Nevada, etc.

In spite of all that, one may guess this memorial will be constructed, probably within five years. To me, at least, it seems fine. I would like to say a few more words about the roses, however, which have not had sufficient thought, and . . .