Tower Built by Vikings? Bubbles Burst a Theory


Most archeologists and historians contend that the circular, 26-foot Newport Tower was built in the mid-1600's for Rhode Island's first Governor, Benedict Arnold, a great-grandfather of the Revolutionary War traitor. But because it has some similarities to Norse buildings, there was some speculation that it was built by Vikings in the early 11th century.

Last week a Danish businessman, who directs the committee of scientists, released results of a two-year study that he said disproved both theories. At a news conference held at the tower, the Dane, Jorgen D. Siemonsen, announced the panel's conclusion that it was probably built sometime between Columbus's first trip to America in 1492 and the Pilgrims' landing in 1620.

Analysis of Mortar

It could have been built any time from 1450 to 1700, he said, "though we can almost with certainty say that it is a post-Columbian tower," built in the 16th or 17th century, most probably in the 17th century. Mr. Siemonsen said these conclusions were based on analyses of the age of the tower's mortar and of the unit of measurement used in building it.

Using technology developed over the last decade at the University of Helsinki, researchers used radiocarbon dating to determine the age of carbon dioxide bubbles locked in 30 mortar samples taken from the tower in January. Each sample weighed about one-third of an ounce.

As a control, mortar samples were also extracted from the Wanton-Lyman-Hazard House, the oldest standing residence in Newport, which is known to have been built between 1676 and 1698 just a few hundred yards away from the tower; the dating system conformed well, Mr. Siemonsen said.

The group also did a computer analysis of photographs to determine what unit of measurement was used in building the tower's windows and pillars. Mr. Siemonsen said the study indicated a unit of measurement called the ell, from Central and Southern Europe, one that was not used then in England. "We would have expected that if they were British colonial builders they would have used the English foot," as was done in constructing the Wanton-Lyman-Hazard House, he said.

The scientific evidence, he said, "brings us to the conclusion that someone built this tower before Rhode Island was settled by the British in 1634."

Another factor in the new dating was the determination that the tower's mortar was made from crushed clam shells instead of limestone. The earliest evidence of limestone's being quarried in Rhode Island was in 1646, Mr. Siemonsen said.

Source: Tracy Breton, "Tower Built by Vikings? Bubbles Burst a Theory," The New York Times, September 28, 1993.

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