IF THERE IS ANYONE still foolish enough to think that a Reagan-Ford ticket and administration would have made sense, particularly with the division of powers which Ford demanded, he should read Robert T. Hartmann's book and be disabused. It is too bad that Reagan and the delegates to the Republican National Convention had not seen the book before the comedy of errors in Detroit over the vice presidency. Hartmann, who was chief assistant to Ford when he was House minority leader and vice president and his chief White House speechwriter, reports that the two men never liked each other.

"There was personal chemistry between Ford and Reagan that complicated everything," Hartmann writes in his account of the office politics of the Ford presidency. The president got along with almost everyone -- except Reagan. Hartmann says that he sat in on many meetings with Ford and Reagan over the years and that "in these encounters both men were usually uptight, unnatural, pathetically polite and acutely on guard. Betty Ford and Nancy Reagan hit it off even worse." "Ford thought Reagan was a phony, and Reagan thought Ford was a lightweight, and neither one felt the other was fit to be president," Hartmann says. "Ford usually wasn't one to harbor mean feelings, but Reagan brought out the worst in him."

Shortly after Ford became president, when he was considering names for the vice presidency, he wrote out five possibilities: Bush, Rumsfeld, Richardson, Rockfeller, Raeygon. He couldn't even spell the hame. Hartmann thinks that if Ford had named Reagan secretary of defense, when he nominated Rockfeller to be vice president, history might have been much different for all concerned. But Ford was not a conniver: it was not in his nature to scheme, to isolate, or bring into camp a potential opponent.

Yet Ford never seemed to take the Reagan challenge to his nomination in 1976 seriously until it happened. Others, including Rockfeller, thought Reagan was sure to make the challenge. Rockfeller, a more experienced national politician with more knives in his back, took Reagan seriously and warned Ford to watch out. But Ford did not move until the challenge was upon him.

This book, which will delight Washington gossips with many other tidbits like these, will enhance Ford's reputation as an honorable man and support those who thought that he was not up to the job. It will supply enemies of Henry Kissinger, Alexander Haig, Ron Nessen and Donald Rumsfeld with new ammunition. Nelson Rockefeller gets high marks but not a perfect score.

Hartmann's book is full of prejudicial judgments and much animosity toward those who competed with him for influence in the Ford White House. Yet it is an entirely honest effort to give a full and accurate account of what Hartmann saw happening. Hartmannn remains loyal to Ford even though he suggests in the book that the president was almost obtuse at times in his appraisal of men and of his handling of subordinates. But Ford knew his own mind, had few if any mental tieups, was generally bluntly honest, trusting and never cunning. According to Hartmann, he was a poor politician in the White House despite his record as a good politican for most of his adult life in Congress.

The Rockfeller story takes up many pages, mostly sad ones, and Hartmann is convinced that the vice president was badly treated by Ford and the White House staff. Hartmann is savage in his indictment of Rumsfeld, Ford's chief of staff and later defense secretary, who he thinks worked constantly to put more knives in the vice president's back. Rockefeller, having lived through the rough politics of New York and the even rougher fighting in presidential campaigns, distrusted men where Ford trusted. Shortly after becoming vice president, Rockefeller told Ford that "there are people you think are friends of yours who want to see you fail in this Administration; who, it you run, don't want to see you get the nomination; and if you get the nomination, they want to see you lose the election."

According to Hartmann, "Rocky named no names. Incredibly, Ford didn't demand them. He didn't even seem very interested in what amounted to a charge of high political treason from his brand-new partner. He reacted with neither annoyance nor alarm. To Rockefeller's amazement, the President simply said he didn't believe that could be the case and went on to another topic."

In large part, Rockefeller's charge of high treason is Hartmann's thesis that the Nixon "Praetorians" left over in the White House and Cabinet ruined good old Jerry Ford. Hartmann argues that even the Nixon pardon, which he thinks Ford handled atrociously, would have been forgiven if Ford had made at the same time a clean sweep of the Nixon operatives and put in his own team. But it was foreign to Ford's nature to fire anyone if it could be avoided. Nixon appointees remained a majority in the White House until the end of Ford's term. "The ghost of Richard Nixon would not go west," Hartmann writes. "His Praetorians dug in to defend their past, their positions, their prerogatives and their power. To them the inexperienced new President was primarily a hostage, and his circle of inexperienced new aides were natural enemies to be quickly disarmed."

One grows tired of reading on page after page of the evil doings of the Nixon "Praetorians." If they were in Ford's way, why didn't he fire them? The answer is an indictment of Ford. Hartmann correctly says that Ford had the right temperament for the task of restoring confidence after Watergate. He practiced openness, consultation, cooperation, consent. But he had never been in command. He had never mapped grand strategy. Those were his weaknesses, which this sympathetic and never-dull book makes manifest. But Hartmann maintains that Ford was a good president, that time might have made him a better president and that many Ford initiatives were sabotaged. Hartmann argues that Ford did have initiative and imagination; then he goes on to demonstrate that he was a poor planner and an "untidy" administrator.

The author, it should be said, wrote the best speeches Ford delivered, but he was never a popular figure in the White House. He writes well even if he does not make friends easily; Ford recognized both qualities in his former aide and current biographer. Whether he will appreciate this frank account is another matter.