The Dream Doctor

There it is, cried Craig scarcely able to restrain himself with the keenness of his chase, ""there it is-the mark like an 'L.' This cartridge bears the one mark, distinct, not possible to have been made by any other pistol in the world. None of the Hep Sings, all with the same make of weapons, none of the gunmen in their employ, could duplicate that mark.
The Dream Doctor is a collection of detective stories featuring Professor Craig Kennedy, who uses his scientific acumen to solve mysteries. A newspaper reporter, Walter Jameson, works with him to get to the bottom of things.
Arthur Benjamin Reeve (October 15, 1880 - August 9, 1936) was an American mystery writer. He is best known for creating the series character Professor Craig Kennedy, sometimes called ""The American Sherlock Holmes"", and Kennedy's Dr. Watson-like sidekick Walter Jameson, a newspaper reporter.