The wind was cold and sharp at Mount Vernon yesterday as Virginia legislators paid homage to the Northern Virginia roots of the nation's first president, but the weather did little to chill the enthusiasm of local politicians over the three-day friendship tour they were staging for the state's General Assembly.

"I think we've shown them that Northern Virginia isn't a monster," grinned Fairfax state Sen. Richard L. Saslaw, one of 26 Northern Virginia legislators who hosted the all-expense paid visit to such local landmarks as Dulles International Airport, the upper Occoquan sewage facility, and the home of Lt. Gov. Charles S. Robb. "People up here don't have horns." t

As the strenuous Chamber of Commerce tour drew to a close yesterday, legislators and state officials said they hoped the trip will mark the first step toward reducing the deep-seated skepticism with which many downstate legislators view their wealthy, urban cousins to the north.

Although many were encouraged about the tour's long-term effects, there was little indication it will do much to help area legislators push their pet legislative proposals this year. "We weren't talking about getting a few bills passed," said Sen. Edward M. Holland (D-Arlington). "We never entertained any delusions that we could resolve the philosophical hangups of the people who run the state of Virginia in a weekend trip."

The regional tour, sponsored by area businessmen at a cost of $70,000, put heavy emphasis on the transportation and housing problems faced by a rapidly growing urban area -- issues over which northern and southern legislators have staged pitched battles for years.

Previous attempts to spread the area's road and mass transportation costs over the state have gotten the cold shoulder from legislators who believe the wealthy Washington suburbs should be able to support the costs of their own increasing density. And despite the vocal expressions of good will that were heard this weekend, it was apparent that local politicians still have a long way to go before they break down the barriers.

"When you have someone who lives on a dirt road that has mud up to the axle when it rains, it's hard to be sympathetic about Northern Virginia's problems," said Claude V. Swanson, a Democrat from rural Pittsylvania, as he sipped a drink at a gala reception in the luxurious McLean home of Lt. Gov. Charles S. Robb.

Fairfax County officials, having given up the highway funding fight in frustration, are now encouraged at indications the General Assembly may grant them authority to use county money to supplement dwindling state road repair funds.

The northerners emphasized the need to boost sagging air traffic at Dulles International Airport, urging that the state take over management of the facility in an effort to steer traffic and development into the Virginia suburbs.

That idea met with little enthusiasm from state officials, who traditionally have cherished a tight-fisted approach to government in the Old Dominion. "I don't see how the state could be in the position of assuming the cost of running [Dullas]," said state secretary for administration and finance Charles B. Walker. "Right now it's not making any money. We'd have to see a lot more than I've seen to demonstate its profit-making potential."

Another proposal, that the state contribute $3.4 million as its share of a sophisticated sewage treatment plant in Prince William County, didn't fare much better after the group took a bus tour of the plant.

Local residents complain that the state government ordered construction of the Upper Occoquan Sewage Authority plant and then declined to contribute its promised ten percent of the $82 million cost of building it. Repeated attempts to win General Assembly approval for funding for the facility have failed.