Sax maniacs can have it all at the free International Saxophone Symposium at the Washington Navy Yard this weekend. It starts 8 p.m. Friday with a U.S. Navy Band concert featuring soloists James Houlik, Brian Sparks and Dale Underwood. Then, from 8 to 5 Saturday: saxophone clinics, workshops, recitals and instrument and music displays. The big event is the closing concert at 8 p.m. Saturday with jazz saxophonist Ernie Watts and the Navy Commodores. Everything's at the Navy Yard's Sail Loft, Building 112, at the Ninth and M SE entrance. 433-6090.


More than 500 cannons were used at the Battle of Antietam. Learn all about them at the Antietam and Monocacy National Battlefield 2 to 4 Saturday when Hagerstown Junior College professor Tom Clemens shows slides and the Baltimore Light Artillery demonstrates a "six-pounder" brass cannon. It's free at the battlefield in Sharpsburg, 11 miles south of Hagerstown off Rte. 65. Call 301/432-5124.


The Eastern Sportfishing and Hunting Show is at the Montgomery County Fairgrounds 9 to 9 Saturday and 9 to 6 Sunday, featuring: free seminars with expert hunters and fishermen of every stripe, clothing displays, equipment demonstrations, plus tackle and hunting gear for show and sale. The fairgrounds are off Rte. 355 in downtown Gaithersburg; admission is $4, under 12 free. 498-2174.


The D.C. Youth Orchestra performs in honor of Martin Luther King Jr. at 6 Sunday with guitarist Bill Harris, saxophonist Andrew White and narration by TV anchorman Paul Berry. It's $8, $3 students/seniors at Howard University's Cramton Auditorium (2455 Sixth St. NW). Proceeds benefit the orchestra. 723-1612 . . . the Orioles Winter Carnival, with pitching workshops, a memorabilia and baseball card show, and hot shots such as Brooks Robinson and Mike Boddicker is 11 to 6 Saturday at the Omni Hotel, 101 West Fayette St., Baltimore. It's $5, $3 for under 12. 301/243-9800 or 301/752-1100 . . . the Annapolis Heritage Antiques Show is at the Medford National Guard Armory in Parole noon to 9 Friday and Saturday and noon to 5 Sunday. Admission is $4.50 to the armory at Hudson and West streets in Annapolis. 301/956-4900 . . . it's all Russian to the Prince William Symphony Orchestra when it performs works by Rimsky-Korsakov, Tchaikovsky and Prokofiev at 8 Saturday at Gar-Field High School, 14000 Smoketown Rd., Woodbridge. Tickets are $8, $5 students and seniors. 703/494-6691 . . . the 27-member U.S. Air Force Singing Sergeants perform at 7:30 Saturday at Wesley United Methodist, 711 Spring St. SE, Vienna (938-8700), and at 4 Sunday at Pohick Episcopal Church, 9301 Richmond Hwy., Lorton (550-9449). Free . . . Birthday celebrations (with guided tours, period music and refreshments) for "Light Horse" Harry Lee and his son Robert E. Lee are 3 to 5 Sunday at the Boyhood Home of Robert E. Lee and the Lee-Fendall House, both on Oronoco Street in Alexandria. Admission to both homes is $4; $2 under 16. 548-1789.


Read any good books lately? Heard any good music? You might try both Sunday at the Library of Congress: The "President's Own" Marine Band will be hooked on classics in its 3 p.m. chamber music recital when they perform works by Hertel, Rossini, Villa-Lobos, Strauss and others in the Coolidge Auditorium. Doors for the concert open at 2:30; the library is open 1 to 5 Sunday. Free. 433-5809.


Young ones can learn a thing or two about Latin American culture at the Smithsonian Resident Associate Program's Discovery Theater. At 1 Saturday, singer/ actor Felix Pitre presents "Spanish Folktales and Songs" as part of the theater's Tapestry series. Included in the bilingual program, recommended for second- through sixth-graders, are songs from Cuba, Mexico and Pitre's native Puerto Rico. It's $3, $2.50 under 12; at the Baird Auditorium of the Natural History Museum. 357-1500.


The Dumbarton Concert Series celebrates its 10th anniversary with a concert by the Empyrean Trio -- National Symphony Orchestra principal pianist Lambert Orkis, associate principal cellist David Hardy and concertmaster William Steck -- followed by a Viennese gala and champagne/dessert reception at the Dumbarton Church, 3133 Dumbarton St. NW. Selections by Beethoven, Brahms, Schubert and others. Admission is $12.50, $6.25 students, free under 12 and seniors. 965-2000.


Help get yourself to the wedding on time by attending this weekend's Washington Wedding Show at the Sheraton Hotel and Exhibition Center, 8500 Annapolis Rd. (exit 20B off the Beltway) in New Carrollton. From noon to 6 Saturday and Sunday, more than 70 companies will be exhibiting wedding accouterments including gowns, tuxedos, flowers, limousine services, catering, video services, photography, silverware and more. Admission is $5. 899-4983.


Combining jazz, blues and contemporary and original acoustic music, the Takoma Park duet Magpie -- Greg Artzner and Terry Leonino -- takes to the stage at 8 Friday to raise money for the Arlington food co-op. The concert, with local folk group Crooked Jack opening, is in Reeb Hall, of the Arlington Unitarian Church, 4444 Arlington Blvd. (U.S. 50 at George Mason Drive), Arlington. Tickets are $7.50 at the door. Call 920-6855.


Kids can groove along with Pegasus at a free concert at 2 Saturday that's part of the "Music of the Spheres" series at St. Mark's Episcopal Church, Third and A streets SE. Flutist Katherine Hay, pianist Frances Thompson McKay and synthesist June Butler will invite children to sing along with them in a program called "The Electric Flying Horse." The program is recommended for kids 8 to 12. Call 546-6252.