Lakes and bogs

[ypk]

In late 18th century people -including eminent men- were searching in lakes/bogs/ponds to find the answer to a question,a mystery. They were not searching for profit. Later on they were ridiculed. What were they searching for?

[Fitzer]

Searching for Swallows? At one point people did not believe that Swallows migrated and that they collected in balls at the bottom of ponds over the winter.

[ypk]

Swallows is the correct answer. They were trying to find out where swallows went when they disappeared!!