Residents of this southern Indiana farming town offer nervous jokes about the 13 dynamite bombs that were found beneath bridges, behind businesses and two historic buildings.

The bombs, traced to a theft of dynamite last month in another Indiana town, were defective and failed to detonate, but the thought of what might have happened has made an impact on the town of 6,000.Patrons at Donanna's Restaurant kidded each other Friday about the 300 sticks of dynamite found with clocks and makeshift blasting caps.

"They'll look under a chair and say `Is there a bomb under here?' and laugh," said Forest P. Noland, a manager at the restaurant.

But, says Noland, "it isn't anything to joke about, really."

Rewards totaling $10,000 have been offered for information about the explosives. The U.S. Bureau of Alcohol, Tobacco and Firearms posted the original $5,000 reward Thursday, and the Indiana Arson Crime Association matched that Friday.

"Now anyone who calls stands to gain $10,000, so maybe it will help," said ATF spokesman Joe V. Thurman.

Thurman said about 35 investigators from his agency, the FBI, the Army and state police were in the town about 30 miles northwest of Louisville, Ky.

On Saturday, Thurman said the dynamite used in the bombs had been traced to a theft at Mulzer Crushed Stone in English.

He said the dynamite, which was stolen between June 6 and 13, also has been linked to a bomb similar to those planted in Salem that exploded along Indiana 37 about a mile south of English on July 1. The town of English is about 30 miles southwest of here.

Three of the dynamite bundles found Tuesday morning detonated partially, producing smoke and small fires.