No one would claim that George Bush and Walter Mondale are the two greatest leaders in American history. But a good case can be made that they are the two most useful vice presidents this country has had, and while some may say that is no great distinction, it represents an achievement that we think ought to be noticed. The more so since we are beginning to see the articles and cartoons that inevitably appear at this stage of the presidential term asking, "Whatever happened to Vice President Whathisname?"

There is a perverse rule in operation here: the usefulness of a vice president seems to vary in inverse proportion to the amount of column inches he gets in newspapers. Mr. Mondale recognized this in the rules he laid down for a vice president: advise the president confidentially and briefly; don't overpraise the president publicly; insist on access to the president, to intelligence information and to key papers, but avoid line authority assignments. These rules almost guarantee a vice president anonymity --but he is the better for it.

George Bush has accepted line responsibilities as head of crisis management, as chairman of the task force on regulatory relief and as coordinator of the South Florida task force. But otherwise he has followed the Mondale formula: the evidence is that Mr. Bush has access to information and to the president, that he speaks frankly to the president in private and loyally about him in public, and that he performs what are staff duties ably and sensitively. Certainly the vice president struck just the right note, at a time when his actions could not have been contrived, in those awful moments of March 30, 1981.

Why has it taken so long to find good use for the position its first holder, John Adams, called "the most insignificant office the mind of man has yet contrived"? One reason is that vice presidents grasped for line responsibilities that inevitably got them into quarrels with Cabinet officials and the man who appoints them. Another reason may be that presidents are naturally jealous of those who are designated as their successors, as so many kings of England have been jealous of their princes of Wales.

The evolution of the vice presidency surely owes something to the good character of presidents Carter and Reagan, and perhaps also to the capacity for principled followership demonstrated by Mr. Mondale and Mr. Bush, who both gained many of their earlier offices at least initially by appointment. In any case, these four men have set a bipartisan model. They are owed thanks for transforming what has long been the vermiform appendix of American government into a useful organ.