A Time Capsule Appeared to Be Full of Dirt. Then, They Looked Closer.

The unveiling of a nearly 200-year-old time capsule yielded great disappointment earlier this week, when the box — opened at the U.S. Military Academy in West Point, N.Y., during a livestream watched by thousands — appeared to contain only dirt.

After days of tense speculation, Paul Hudson, the academy’s archaeologist, peered into the roughly one-foot-square lead vessel with a flashlight and soon declared that “the box didn’t quite meet expectations.”

As it turned out — Mr. Hudson just had to look closer.

After Monday’s event, Mr. Hudson returned the box to his lab. The next day, he dug deeper into the container and unearthed six silver coins dating from 1795 to 1828 and a commemorative medal from 1826, Jennifer Voigtschild, the academy’s command historian, said on Thursday.

In the moments after the box was first opened, Ms. Voigtschild said, she felt “baffled that there would be this very, very, well constructed box, that would have nothing in it.” But, she said, as Mr. Hudson began removing pieces of matter from the box while onstage and examining them, her hope was somewhat revived.

“I was like, ‘OK, there is something in there. We just don’t know what it is.’”

Military experts believe that the box — discovered earlier this year during repairs to an on-site monument of the Polish military engineer Tadeusz Kosciuszko — dates back to 1828. Kosciuszko, a hero of the Revolutionary War, helped to fortify West Point, a feat widely credited with keeping British forces at bay. His eight-and-a-half-foot bronze statue was designed in 1822 and mounted on the column where it currently stands 85 years later, according to the academy.

But it is unclear when or why cadets decided to put the box inside the base.

The hype was considerable leading up to Monday’s event; guesses of what the box might contain ranged widely and included the Ulysses S. Grant’s beard trimmers, a map of underground steam tunnels and the original recipe for West Point’s corn chowder.

In a promotional video, one cadet excitedly guessed the box held a pair of boots; another said that perhaps it was “a really cool class ring.”

“I guarantee it’s gonna be better than Geraldo,” Superintendent Lt. Gen. Steven Gilland told the crowd before the reveal, referring to the 1986 opening of Al Capone’s vaults, which, hosted by the commentator Geraldo Rivera, uncovered little but dirt.

The box, shrouded in a black cloth, took center stage among the academy’s elite, including Mr. Hudson, who held it still with gloved hands as a colleague pried the lid off with a chisel.

“What do we see?” Ms. Voigtschild asked at the event. Mr. Hudson peered into the box with a flashlight as the camera panned over the seemingly cavernous opening. The crowd laughed. Mr. Hudson switched off his flashlight and let out a “Hm.” Others approached the box to take turns peering inside.

“Paul and his panel of experts are discussing the best way to find what may be in the box. We don’t want to hurt anything that might be in there,” Ms. Voigtschild said as the livestream continued. After a long pause, she added, “if anything.”

Later onstage, Mr. Hudson acknowledged that the results had been somewhat disappointing. The next day, however, he would return to the task, carefully sifting through the rest of the sediment with a pick and a brush.

“I’m brushing and brushing and I’m just thinking, ‘Oh, it’s, you know, sediment; I’m gonna pull out all this sediment,” Mr. Hudson said by phone on Thursday. But then, he said, “out pops the edge of a coin.”

The investigation is still in its early stages, he said. He still wants to know: “What is this sediment doing in the box?” Theories include that the dirt had washed in from outside, or that it could be organic material, like a letter that had disintegrated over the years.

“Once we establish that,” he added, “then we can start answering those bigger questions, and more abstract questions about why did they put it in here.”

The discovery of the coins and medal was bittersweet, Mr. Hudson said, noting that it was largely by chance that he had not discovered at least one of the objects when there was an audience.

“If it had been like that on a stage, that would have been great,” he said.