The Williamsburg branch building of the Brooklyn Public Library, Brooklyn, N.Y., had an interesting situation arise in late 2004. The staff was told that a time-capsule had been placed within one of the cornerstones of the library by Andrew Carnegie in 1903. The 26,000-square-foot brick building was officially opened in 1905 and was set to be rededicated in 2005, but not much thought had been given to the time-capsule over the past 100 years.

Finding the spot where Carnegie placed the time-capsule became a perplexing issue because no one knew the exact location. The library realized that this type of challenge was best handled by masonry professionals, so they called in an engineering firm to help locate the capsule.

The engineering firm believed that ground penetrating radar (GPR) was the safest way to non-invasively inspect the brick building for inclusions while getting accurate location results.