The dollars exchange rate has now been sliding downward for six weeks. It's been a rather rapid decline, but it's been orderly and serene. The exhange rate is back roughly where it was late last autumn -- still too high, but moving in the right direction.

For this improvement, much of the credit goes to the state of Ohio and its savings and loan crisis. That was the event that brought the dollar off its perilous high in early March. The rumors of impending failures, and the governor's dramatic decision to close the state-insured S&Ls, caught the attention of foreign investors and set them to wondering whether they really wanted to keep pouring their money into the United States.

By pure luck, the Ohio affair was a crisis of just the right size. It was sufficiently serious to make money managers a little more cautious about piling up their dollar holdings endlessly. But it didn't do much permanent damage. It broke the momentum of a speculative surge into the dollar. But it didn't set off a panic, or start the flight from the dollar that has become the nightmare haunting this country's mismanaged foreign accounts. As financial earthquakes go, this one was low on the Richter scale. Everybody felt the tremors; there was some broken glass but no structural damage.

Next, the Commerce Department published the first preliminary estimate of the country's economic growth rate in the first quarter of this year. It turned out to be much lower than most investors had expected and warned them that the prospects for profits here might not be quite so certain as they had thought. The dollar kept declining.

No one knows whether it will keep going down or, once again, reverse itself. The rate is being set in the daily trading of currencies throughout the world and no authority controls it. The dollar is still substantially overvalued in terms of the goods that Americans buy and sell. If it continues to drop, the effects will depend on timing and the relation to action on the federal budget deficit here in Washington.

If the administration succeeds in reducing the budget deficit and the Treasury no longer needs to borrow at the present gigantic pace, American interest rates will come down and the foreign money bags, looking for high returns, will go elsewhere. But if the dollar drops while the federal government is still running deficits over $200 billion a year, the consequences will be unpleasant. A falling dollar will frighten off the foreign investors who have been sending their money here. In the absence of the money that they have been pouring into the American credit markets, interest rates here will rise sharply and threaten another severe recession. The financial movements can swing very fast while, unfortunately, te administration is making only slow progress with the budget.