What is a technique used by Holmes to solve the crime in "The Adventure of Black Peter" by Arthur Conan Doyle?
One of Holmes’s favorite techniques is disguise. His disguises are so good that even Watson sometimes does not recognize him. In disguise, he can travel freely. Watson notes that Holmes has become more and more famous, so it makes sense that he would need to disguise himself more frequently.
… Holmes was working somewhere under one of the numerous disguises and names with which he concealed his own formidable identity.
Holmes is able to go around in disguise in order to collect information. He also has a variety of disguises that allow him to visit places unnoticed.
Holmes does not let Watson in on his plans, and Watson does not ask. This of course allows the reader to be even more in the dark, adding to the story’s suspense.