The Chronicle explains how the box full of ancient mementos was discovered:
Former Cleveland student and now school volunteer John Weidinger discovered the time capsule's existence while researching the history of the 100-year-old school.
The capsule was mentioned briefly in a San Francisco Call newspaper story at the time, saying then-Mayor P.J. "Pinhead" McCarthy placed the box behind the cornerstone after the children sang "The Star-Spangled Banner." It didn't say what was inside.
"Had I not found that one sentence, maybe we might have lost that part of San Francisco history," Weidinger said Wednesday moments before he pulled the contents out of the box in front of the students.
During the school's winter break, district carpenters cut around the cornerstone and confirmed the box existed. It took two more days to drill the box out of concrete while protecting the cornerstone.