Not the First Time
As it turns out, this was not the first time that the time capsule had been discovered. There was a time previously when the box was found. In 1855, 60 years after it had been originally placed inside the building, a group of workers came across the mysterious box. They took out the items from the box and put them all inside a stronger brass box with a bunch of new items.
Source: Drivepedia
The Governor at the time, who was Winslow Harley, took the capsule and organized a ceremony. He then placed the box back inside the cornerstone of the building. And then 159 years later, the box was to be discovered again.
And the box was found under similar conditions…