In The Red-Headed League why does Sherlock Holmes beat upon the pavement outside of Jabez office?

In "The Red-Headed League," Sherlock Holmes beats upon the pavement outside of Jabez Wilson's office to determine if there is a secret passage underneath the building.

Here's why:

* The Clue: Holmes had observed that the pavement outside Jabez's office was uneven, with a section that seemed to be sunken. This unusual feature piqued his interest.

* Testing the Theory: By beating on the pavement, Holmes hoped to hear a difference in sound between the solid ground and any potential hollow space underneath.

* The Outcome: Holmes's suspicions are confirmed when he hears a distinct, hollow sound coming from the sunken area. This leads him to believe that there is a passage beneath the pavement, which is ultimately used by the criminals to access the bank vault next door.

This method highlights Holmes's keen observation skills and his use of deduction to solve the mystery.