THE THING about presidential transitions is that they are both too short and too long. They are too short to get everyting arranged as tidily as most incoming administrations would like, and too long to satisfy the national urge to get on with the public business. Since we give vent to this lugubrious editorial thought during evey presidential transition, it seems only fair to concede that, to date, we have been able to think of nothing much in the way of remedy. It is of course true that on one desperate occasion we were incautious enough to speak admiringly of the heartless British system, wherein the first sound a defeated prime minister is likely to hear above the decorous sobs of his loved ones is the roar of a moving van approaching his Downing Street residence. But for a number of obvious reasons one wants to be cautious about emulating our British cousins these days. And in any event it may no longer be necessary. The transition case seems to have been cracked in the 1976-77 variation. The transition has simply been wished and willed away.

Consider it. The whole nation, with the possible exception of an uncharacteristically obdurate Gerald Ford, seems to have decide to conspire in the fiction that Jimmy Carter is already President. Has he not already held "a cabinet meeting,'g so described by the press and so referred to by members of Congress who, in other days and times might have got just a trifle sniffy about "cabinet members" who have not been confirmed by the Senate? Never mind - the "cabinet" has met. There has been, in addition, a meeting of the Carter administration national security council. There is an economic plan. And lest anyone think this whole illusion of ensconcement has not caught on, it should be pointed out that the predictable first wave of liberal disenchantment with the Carter administration has not only occured, but has already shown signs of subsiding.

Now, from Mr. Carter's point of view, there is obviously merit to all this. What could be more useful than having the first wave of liberal disenchantment roll in and roll out two weeks before one takes office, as distinct from three months later? And what could do more to strengthen the chances that your more controversial nominees will be confirmed than the creation of an illusion that they already have been? Does anyone really want to remove Attorney General Bell from office or dislodge Mr. Sorensen from the CIA? How reckless can you be? Have not the Justice Department and the CIA been through enough in the past decade?

Alone against this tide if suggestibility, as we said before, stands the lonely figure of Gerald Ford - generously welcoming Puerto Rico into the union, earnestly porposing inequitable and regressive new tax laws and cranking up further to do God only knows what before his next nine days run out. In principe, if not in substance on his proposals, we are with him. We prefer to take our administrations tidy and installed.