"Rivers are ungovernable things. Canals are quiet and very manageable." --Benjamin Franklin.

The tranquility of a canal makes it a fine place for a park, to be enjoyed archeologically, historically or just recreationally. Five 18th- and 19th-century canals offer all these possibilities within a reasonable drive -- two are in our own backyard, one is in Richmond and the other two are in northeastern Maryland.

Along the river at Great Falls Park, Virginia, stands one of the canals built by the Patowmack Company, of which George Washington was president just before he became President. Early on as a surveyor, he envisioned the Potomac as a route that would connect the colonies to the western settlements; canals would have to be built around rough water. This canal was begun in 1786, but not opened until 1802. "How do people conceive of this being a historic transportation route?" George Higgs asked one afternoon as he walked through underbrush beside one of the five locks on the passage around Great Falls. A civil engineer, now retired, Higgs has adopted the Patowmack Canal, and to be sure that interest in the canal is maintained, he founded the Virginia Canals and Navigation Society. Every Saturday at 11, somebody from the society leads a walk along the canal. Higgs' dream is that one day the National Park Service will reactivate a lift lock and institute boat rides here, as on the other bank. Now, though, water flows only through the first few hundred feet of the canal. Higgs' immediate concern is trees that are growing out of the old stone walls: "When they topple over, they take a piece of wall with them," he says. Some trees have recently been removed; the stumps look odd, tucked into the walls, clutching the stones. Like the Smithsonian castle walls, the locks were made of red sandstone from Seneca, a few miles upriver. Markers dot the mile-long route from a wing-dam down to the gorge. One explains the remains of buildings of Matildaville, founded in 1790, and visible along the stretch of what was the old turning basin. The Patowmack Company didn't prosper; the C&O Company bought it out in 1828, and the canal closed by 1830. Matildaville, the company town, fell into ruin. Matildaville stirred Higgs' interest in the canal. Loafing around the house, he says, he found a book on Revolutionary War general Light Horse Harry Lee. Noting in the book that Lee had bought some land around Matildaville, Higgs went up to see for himself. "I was appalled at the amount of deterioration that had taken place," he recalls. An excavation last year uncovered lock gates and part of a canal boat or "sharper." These can be seen in the visitors' center, where they're being treated with preservative for a year or two. A good view of the Great Falls can be had from a nearby overlook. The falls were, after all, the reason for the canal. Two points for the visitor: You don't have to pay, as you once did, to park at Great Falls, Virginia; you do have to wear long pants, especially if viewing closeup the magnificent specimens of poison ivy.

Across the river, the 1841/2-mile-long C&O Canal park overshadows any other canal park around here. The section from Georgetown to Seneca alone has 24 locks, and two canal boats ply these waters. Along with biking, canoeing, fishing, hiking and picnicking, there's endless scenery. One of the finest stretches of it is the section called Widewater. To reach it, pick up the towpath at Great Falls, Maryland, or at Old Angler's Inn, both accessible from MacArthur Boulevard. Along the quiet path, black swallowtails dance and fish leap into the air. Rocks are gathered by the water like supplicants waiting for baptism. Yellowjackets lie in ambush at trail markers, but no matter. This two-mile stretch holds locks, a lockhouse, the entrances to the Billy Goat Trail (a rocky hike along the river reserved for sturdy constitutions and sturdy shoes -- watch out, people have died thinking they could handle this), a view of the river and Cupid's Bower (impressive rock face), a concrete bridge, a stop gate and the C&O Tavern. The tavern was built between 1828 and 1831, serving as inn and lockhouse. Included in its exhibits are a model of canal boats passing through a lock, an indenture agreement for one John Rowley of England in 1829 to work three months as a mason on the canal in return for passage, an ale bottle, clay marbles, a lantern and a crew member's false teeth. Rangers at the information center here will answer your questions. A number of paperback books on canal lore are sold here, the popular item being the Towpath Guide to the C&O Canal by Thomas F. Hahn. Mile by mile, the guide explains every possible point of interest: ruins, waste weirs, historic culverts, bird sightings. It's invaluable to the canal enthusiast. Park ranger Gary Pieruccioni recommends three nearby points you wouldn't want to miss. First, there are actually two different kinds of locks on the C&O: the typical swing- gate lock and the drop-gate lock. Locks 7, 9, 10 and 12 are outfitted with drop-gates, a technological advance that speeded up the locking process in the Seven Locks area where there's a high concentration of locks. Major engineering feats are the aqueducts at Monocacy and Seneca. And if you stop by Seneca lockhouse Saturdays or Sundays from 1 to 4, you'll see Girl Scouts in 1870s garb performing a living-history program: scrubbing clothes, churning butter, quilting, making sachets. At the Tavern, a program on sights and sounds along the canal is scheduled for the first and last Wednesday and Saturday of the month. And, running about every two hours Wednesdays through Sundays, are the canal boats; tickets are $4 for adults, $2 for children. One boat leaves Great Falls Tavern and goes as far north as the mules feel like going that day. The other starts in Georgetown, between 30th and Thomas Jefferson streets NW. This one offers a waterside view of all the changes over the years -- at Conran's, where the boats used to be moored, at the Foundry Restaurant, where there was once a mule hospital. As you'll hear on the boat rides, families lived on board from March to December. Children too small to work were tied to a post so they wouldn't fall overboard.

Because the canal operated until 1924, there are still people alive who recall the way of life along the C&O. But when personal recollection isn't available, there are other methods for learning more about canals. Last month, several old canal boats were uncovered at a construction site in downtown Richmond -- where a basin had been on the James River Canal, thought to be the country's first canal system. One, a coal boat, dates back to at least 1800, says William Trout, president of the Virginia Canals Society and vice president of the American Canal Society. Trout, 46, is on leave from his geneticist's job to write a book on canals, something he's been interested in since his Boy Scout days. Instead of experimenting with fruitflies, he's investigating canals. If he and a friend hadn't been nosing around the site and asking the workmen what they were finding, the boats would probably still be under silt. One of the uncovered boats has a hearth: "Nobody's ever seen this sort of thing before," says Trout. "Every boat has something different about it." In addition, workers have dug up lanterns, a grappling hook, bars of pig iron and a parasol. Though an office building is rising there (at Canal Street between Ninth and Tenth), Trout isn't discouraged. There are two more blocks of the three-block-long former basin yet to be excavated. Trout says plans are for the coal boat to be kept in water at the lock in one of Richmond's two canal parks -- the Tidewater Connection Locks Park, at 12th and Byrd streets. Reynolds Metal Company owns the park, which has a self-guided tour and displays. (a roThe other Richmond canal park is the Great Ship Lock Park at the foot of Pear Street off Dock Street. Still operable, this lock is the last stage, the one that lowered the boats into the James River.

In Maryland, Havre de Grace was the location of the first lock on another historic canal, the Susquehanna and Tidewater Canal, which covered 45 miles to Wrightsville, Pennsylvania. In a park at the edge of the Susquehanna, you can still see the first lock, (and upriver, remains of other locks) along with a large lockhouse, where the lock-tender lived. Open Sundays from 1 to 5 into December (or until it gets cold), the lockhouse has been restored, with furniture appropriate to the canal's years of operation, 1839 to 1900. From time to time, a local historical society changes the displays, which may include period dresses, old Havre de Grace street signs, antiques toys, decoys or quilts. There's fishing on the river and picnicking on the grass, in an area crossed by four bridges. As you drive toward the lockhouse and pass below a railroad bridge, likely as not an Amtrak train will blow its horn above you as it rumbles across town. People who live there say they aren't aware of it. "It's just the new people that notice it," says Mary Lynn Snyder, a local real estate agent. "I love it. It's exciting." The railroad is also the reason we are visiting canals that used to be for commerce: Trains just move faster than canal boats, and there was no holding them back. Before a proper rail bridge could be built, trains crossed the Susquehanna on barges in the summer, and in the winter, track was laid across the ice. To further illustrate the competition, the B&O Railroad and the C&O Canal began construction on the very same day -- July 4, 1828 -- often vying for the same slip alongside the Potomac.

East of Havre de Grace, starting in Chesapeake City, Maryland, is the Chesapeake and Delaware Canal, opened in 1829. Connecting the Delaware River to the Chesapeake Bay, this canal is still very much alive as Philadelphia's back door to Baltimore. In the old days, the 14-mile-long canal across the Maryland-Delaware isthmus brought showboats and floating stores to residents of its shores. There were four locks -- one of which can still be seen in Delaware City -- and a pumping plant at Chesapeake City, where the C&D Canal Museum is now located. Along with the pumping machinery, the museum displays memorabilia and models of the craft that plied it. When the canal lost water through evaporation, drought, leakage or the locking process, the pumping plant drew water from a side channel and dumped it into the canal. The buckets of its steam-operated waterwheel carried a million gallons an hour. Eventually, pumping was no longer needed. In 1919, the canal was purchased by the United States to become a link of the intracoastal waterway, and the Corps of Engineers, by deepening the channel, converted it to sea level by 1927, obviating the need for locks. But, somehow, a canal just isn't as interesting without them. WHERE TO GO CHESAPEAKE & DELAWARE CANAL MUSEUM -- Chesapeake City, Maryland. Pumphouse hours: Monday-Saturday, 10 to 4:15, Sunday, 10 to 5. Phone: 301/885-5621. C&D CANAL CRUISE -- For a closeup look at the Chesapeake & Delaware Canal, Baltimore Harbor Cruises has planned 12-hour excursions for October 2 and 16. The triple-decker boat leaves the Inner Harbor at 9:30 a.m. Admission is $13.75 for adults; $6.85 for kids five to 15; under five, free. Bring your own lunch. Phone: 301/727-3113. C&O CANAL BARGES -- For recorded schedules, call 472-4376 (The Georgetown) or 299-2026 (Canal Clipper at Great Falls). GREAT FALLS PARK -- north end of Old Dominion Drive, Virginia. Open 8 until dark. Phone: 759-2169. GREAT FALLS TAVERN -- north end of MacArthur Boulevard, Maryland. 9 to 5. 299-3613. SUSQUEHANNA LOCKHOUSE MUSEUM -- Havre de Grace, Maryland. Sundays, 1 to 5. 301/939-5780. WHERE TO WRITE AMERICAN CANAL SOCIETY -- For information, write William Shank, president, 809 Rathys. (a roton Road, York, Pennsylvania 17403. C&O CANAL ASSOCIATION -- For details, write to Box 66, Glen Echo, Maryland 20812. VIRGINIA CANALS & NAVIGATION SOCIETY -- For a free pamphlet, "Canal Parks in Old Virginia," send a stamped, self-addressed envelope to 35 Towana Road, Richmond, Virginia 23226.