PHILIP CALDWELL, Ford Motor Co. chairman, said, after looking over Mount Vernon's financial statement, "'The Mount Vernon Ladies' Association [owner of the estate] should be running Ford Motor Co."

Washington, a firm believer in property as a measure of wealth, undoubtably would be pleased at the prosperity of his estate. Mount Vernon is second only to the White House in the number of visitors -- more than a million last year. (The White House is free.)

The admission fees ($3 for adults, $2.50 for senior citizens, $1.50 for children) alone amounted to $2,512,426 last year, giving it probably the healthiest financial condition of any historic house, according to John A. Castellani, Mount Vernon's director. "Mount Vernon supports itself. Our budget yearly runs about $2.5 million to $3 million depending on how much we took in the year before."

Last year, Mount Vernon's finances were so good, it was able to buy the lease to the Mount Vernon Inn and Gift Shop, just outside its gate, for almost three-quarters of a million, Castellani said.

Even so, Mount Vernon has launched a $10 million campaign, its first since the 1853 when the Ladies' Association raised $200,000 to buy the estate. Treasury Secretary Donald T. Regan, a neighbor of Mount Vernon, is honorary chairman. Robert A. Beck, chairman of Prudential Insurance Co., is the active chairman.

Of the $10 million, $4 million will go to set up an endowment for the historic property against lean years (it already has a $2.3 million operating reserve). The rest will go to capital improvements. Frances Claiborne Guy, the regent of the association, said, "The Mount Vernon Ladies' Association does not want to ask the public to pay for the full cost of these improvements through greatly increased admission fees, as this would deny some visitors access to George Washington's home."

The largest single cost is the $2,789,000 to pay for the new library and research center, with an elaborate archival climate control comparable to today's presidential libraries. The archives include more than 500 letters of the Washingtons as well as 14,500 diaries, plans, surveys and accounts. The Ladies' Association's own papers, documenting the beginnings of historic preservation in this country, amount to 500,000. The center, in a design compatible with Mount Vernon's period, but not a pastiche, is already more than half completed.

The old administration building will be used for public restrooms with facilities for the handicapped (the present service is down a flight of steps), association receptions, security headquarters, sales and storage.

A new entrance gate following a plan of Washington's has already been financed by a gift from the William Randolph Hearst foundation.

About $3.5 million is earmarked for systems improvements.

Updating the electrical system for the 42 buildings on the estate will cost $515,000. The electrical system, originally installed in 1922 by Thomas Edison himself, has been redone twice before. "The 1940s installation," Castellani said, "was so extensive, with tunnels for servicing the heat and electricity, that we are able to update our plant without any problem."

Two years ago, the heating system was switched over to natural gas from coal.

The new fire protection should cost $265,000. Recently, Ford Motor Company gave an $80,000 fire engine to replace the 1936 model. An elaborate fire protection system designed to prevent the sort of fire that recently devastated F.D.R.'s Hyde Park home was installed in 1979. The system uses Halon 1301, a gas like Freon but not as lethal.

The new $280,000 security system will cover the vulnerable areas. A $350,000 production greenhouse will raise plants for the house and to sell. The proposed irrigation system through the visitor grounds will cost $100,000. A three-year archeological survey, the first complete one, including marine archeology, is expected to cost $350,000. A generous $1,300,000 is allowed as a provision for inflation and campaign costs.

"We are in good financial condition now, but we think we owe it to the future to establish an endowment," said Castellani. "There's always the possibility of a year like 1973, when our attendance dropped 49 1/2 percent because of the gasoline shortage."

"Mount Vernon, because we can't put it up for collateral, can't borrow money, even for capital improvements," he noted.

So far, the historic association has already raised $3.5 million, and the corporate campaign is just beginning. A campaign by American Express, in which 3 cents will be given to Mount Vernon every time an American Express card is used, is expected to net a considerable amount, especially since Hecht's Woodward & Lothrop, Marriott Dominique and Richard's Pier 20 restaurants are adding to the American Express contribution.