THE man who after the US president is "arguably the nation's most powerful person" - and this week true to form nudged interest rates higher - does much of his real work in the bathtub.

Mr Alan Greenspan, Chairman of the Federal Reserve, discovered in the 1970s that long, early morning hot baths not only soothed his back but stimulated his thinking. So he sits in the bath for an hour and a half with his in tray, adding hot water and drafting speeches.

His companion of the past 12s years, the high profile NBC reporter Andrea Mitchell, goes for a run while Greenspan ponders the future of the US and the world economy. They will marry on April 6th.

The Fed's independence and control of interest rates gives 71 year old Greenspan a unique role in American economic life and more controversially in political life. His determination to conquer inflation in the 1980s through a series of interest rate hikes steadied the economy but left George Bush vulnerable to his challenger Bill Clinton as unemployment peaked in election year.

Republican Greenspan who had worked for presidents Nixon, Ford and Reagan went on to establish a smooth relationship with Democrat President Clinton under whom there has been record growth and job creation.

But now critics grumble that Greenspan has become too interventionist. There was the famous reference in a recent speech to the "irrational exuberance" of Wall Street which caused a temporary panic on the markets.

Mr Greenspan's lobbying for an adjustment in the Consumer Price Index (CPI) as a way of reducing the budget deficit is also resented in some quarters. Mr Robert Solow, a Nobel laureate economist, says Mr Greenspan is only using the ambiguous kind of language practised by Fed predecessors.

"They've all mastered the art of meaningless verbiage. That's part of the normal manner of a chairman, to appear to be saying something while you're saying nothing at all". Mr Solow says that "Alan is the past master of this. It's what central bankers do. They're like squid, they emit a cloud of ink and move away."

Mr Greenspan enjoys Washington parties with Mitchell, 21 years his junior, and they have some close journalist friends although he never gives interviews on the record. Behind the donnish demeanour is a man who once wanted to be a professional musician.

As a student in New York he played the clarinet and tenor saxophone. His mother taught him tennis which he still plays with "sneaky left handed slices" according to Mitchell.

For a year in the 1940s, Greenspan played for the Henry Jerome swing band. He was hired by Leonard Garment who would later become Richard Nixon's law partners and bring Greenspan to the Nixon White House.

But after a year with the band, Greenspan entered New York University where he got a master's degree in economics in 1949. He began a doctorate in Columbia but had to leave to make a living and was finally awarded the PhD in 1977.

His marriage in 1952 to painter Joan Mitchell lasted a year but she introduced him to the Russian writer and philosopher, Ayn Rand, whose ideas on "objectivism" or enlightened selfishness is said to still influence him. Greenspan also became a millionaire through a Wall Street consultancy.

Through the Garment connection, Greenspan met Nixon who appointed him to chair his Council of Economic Advisers in 1974. Nixon resigned before Greenspan was confirmed but his successor, Gerald Ford, kept him and they became close.

Ford thinks that Greenspan's sensitivity to the public mod comes from meeting people as he played in his band's one night stands. One is tempted to compare this with Albert Reynolds's experience as dancehall owner and later re incarnation as Minister for Finance.

But just now, some people feel Mr Greenspan could be more sensitive to the nerves of stockholders when he comments on Wall Street living dangerously.

A Republican Kentucky congressman, Jim Bunting, openly challenged Greenspan: "Why have you taken to jawboning the US stock market and bond market with your comments?" He went on to accuse Greenspan of improperly meddling with the "free and open" financial markets.

Maybe it is time to have another hot bath.