Given the rules of the Barnes Foundation, reservations are a decided advantage for anyone making a day trip from the Washington area -- particularly since the advance-notice requirement grows ever longer: Last winter, applicants were asked to reserve, either by mail or by phone, three weeks in advance; by this spring, it was "several weeks in advance."

For risk-takers and the impulsive, there is hope -- entry for 100 visitors without reservations is permitted on Friday and Saturday and for 50 on Sunday. But drop-ins who want to see the entire collection are advised to arrive early.

While this state of affairs does not encourage spur-of-the-moment visits, Philadelphians have developed a strategy that works nicely if you are staying overnight in the area. Because the viewing day is divided, with the average visit taking three to four hours, aficionados tend to take a chance on admission as soon as the gates open at 9:30 a.m., leave for an early lunch (reentry is permitted) and return in time for the 1:30 opening of the rest of the rooms.

Large groups are not permitted on Sunday, and reservations for groups should be applied for in writing "months in advance," according to a recent phone inquiry. In fact, requests for reservations for groups are sometimes refused. On the bright side, according to the jovial guard at the gate, a group of up to 25 may be admitted on a first-come basis in the morning and afternoon on Friday and Saturday -- never on Sunday. The foundation is closed July and August.

GETTING THERE: If you are making a day trip from Washington, an early start is a necessity if you are to reach the Barnes Foundation by 11 a.m. at the latest, in time for a quiet walk-through. Merion Station is just southwest of the Philadelphia suburb of Bala-Cynwyd. From I-95 North, Exit 8, take Route 202 north through Brandywine country to Route 1. Turn right and follow Route 1 for about half an hour -- it becomes Country Line Road -- then turn left onto Old Lancaster Road and left again onto North Latch's Lane to the Barnes Foundation. Or stay on I-95 to Philadelphia, exit onto Route 76, an expressway that crosses the city to Route 1 (a left turn). From Route 1, take a right onto Old Lancaster Road and a left onto North Latch's Lane.

INFORMATION: Phone inquiries and reservations, (215) 667-0290. Reservations by mail, the Barnes Foundation, 300 North Latch's Lane, Merion Station, Pa. 19066.