LBANY, Nov. 23 — What were the words to that song? Fifteen miles on the Erie Canal? Today, Stephen Jones went 15 centimeters, maybe 20, on a trip that was frustrating in a so-near-and-yet-so-far kind of way: he did not find the one thing that maps and charts and careful calculations had convinced him was buried right beneath his feet.

What he was looking for was a remnant of the original Erie Canal, the 363-mile liquid highway that opened the way to the Midwest in the 19th century. Specifically, Lock No. 53, a wood-and-stone bulwark that lowered boats heading south to the level of the Hudson River and raised Buffalo-bound vessels for the trip along the high and mighty Erie.

"It's tough digging," said Dr. Jones, a visiting professor of anthropology at Union College in Schenectady.

His work carried him vertically through layers of soil, instead of horizontally along the canal that Thomas Jefferson dismissed as "little short of madness," but if Lock No. 53 eluded Dr. Jones and his colleagues from Union College, other fragments of the canal have not. In two years of archaeological detective work in a neighborhood of warehouses and vacant lots about a mile from the State Capitol, they have uncovered evidence of a weigh lock, used to help canal operators decide what tolls to charge. Nearby, they discovered the foundation of a toll collector's house, a grand-looking structure with columns.

And last month, about 200 feet from the pit for Lock No. 53, they found the smooth granite blocks that topped a wall of a lock from a later version of the canal.

"This is the start of everything," said Denis Foley, a Union College research professor in anthropology, showing off the top of the lock wall. "The start of the westward movement. This is what made New York the Empire State. This is what made New York City the pre-eminent commercial city in the United States."

The history books tell the story: the Erie Canal came along at just the right moment, and was the first important national waterway built in the United States. The laborers who laid out the locks and installed the equipment that made them function were working in the wilderness — there were no roads to haul in the supplies needed to build the canal. Their champion was De Witt Clinton, who by the time the canal opened had been mayor of New York City and governor of the state. His enemies tried to laugh off the canal as "Clinton's Ditch."

But it quickly became a moneymaker. It also lowered the cost of shipping raw materials (the cost of transporting flour had fallen to a penny a ton by 1830) and cut travel time between here and Buffalo to six days, from two weeks by wagon.

It opened in 1825 with Clinton making an inaugural trip from Buffalo to New York City. His departure was signaled "by the booming of a line of cannon stationed at suitable intervals all the way across the state to Albany and down the Hudson." So declared Roy G. Finch, the state engineer and surveyor, on the canal's 100th anniversary. Finch called the celebration "a grand salute 500 miles long, announcing to the people of the state the completion of the most stupendous undertaking of their time."

Soon America was going canal crazy, building more than 4,000 miles of waterways and opening back-country towns to hard-drinking, hard-driving barge captains. The Erie was modernized and rerouted twice to handle larger vessels and more traffic, but only short stretches of the latter-day New York State Barge Canal System follow the channel dug for the original Erie. Each time the canal was recast — in the 1840's and again between 1905 and World War I — the engineers figured out how to make do with fewer locks, ultimately trimming the number to 35 from 83.

The hunt for the old Erie began with Dr. Foley and F. Andrew Wolfe, the chairman of the civil engineering department at Union College. Copying old maps and matching them against modern ones, they calculated where the locks had to have been. The maps were not always reliable — "The streetscape has changed," Dr. Foley said — and a 1972 study said the structures from the old Erie had been demolished.

Still, after digging a few test holes, they found Lock No. 1 next to a parking lot. That discovery led them to press on toward Lock No. 53. They knew they were in the right area because the maps showed both locks in the same milelong basin that was in effect a changing area.

The mules that had pulled canal boats from Buffalo were unhitched where the archaeologists had been digging, Dr. Wolfe said. From there the steam-powered predecessors of tugboats took over for the ride down the Hudson to New York.

"We thought that, since we know all the measurements, why don't we find the original canal?" he recalled.

Off to the woods, and the pit where Dr. Jones was digging for Lock No. 53 (on the original Erie, the locks were numbered east and west from Rome, N.Y.). Dr. Jones found bits of clay pipes like the ones 19th-century canal users would have smoked and tossed overboard. Also in the pit was an iron handle that looked like one end of a shovel. Dr. Wolfe speculated that it was part of a hay-bale pick.

So was there anything else down there? Dr. Wolfe wanted to know what Dr. Jones had been finding.

"Slag, slag and more slag," he said. "There's no industry recorded as being close to here to explain this type of slag, but that's archaeology for you. You always find more questions than answers."