The search using ground-penetrating radar comes in conjunction with tomorrow's 175th anniversary of the birth of the monarch, who died in 1872 as the last direct descendant of Kamehameha the Great to rule the Kingdom of Hawaii.

Historians know the capsule was buried Feb. 19, 1872, and contains priceless pieces of the islands' rich royal history more than two decades before the kingdom was annexed by the United States. But they do not know its exact location.

The capsule was buried during a celebration in which Kamehameha V laid the cornerstone of the historic Aliiolani Hale building in downtown Honolulu. The small casket is believed to be beneath heavy concrete slabs on the building's northeastern corner.

It contains photos of royal families dating back to Kamehameha the Great, Hawaiian postage stamps, a constitution of the Hawaiian Kingdom, 21 Hawaiian and foreign coins, 11 different local newspapers, a calendar and books such as a Hawaiian-language dictionary.