The Thinking Machine: Adventures of a Mastermind
by Jacques Futrelle.
Originally written during the first decade of the 20th century, the Thinking Machine stories introduced one of the first story-book scientist-detectives (alas, they don’t really make them like this any more.) Professor Augustus S.F.X. Van Deusen, a.k.a. The Thinking Machine, uses his great powers of logic and deductive reasoning to solve crimes and other problems.
These stories are great fun and although they require some stretches of imagination, they are on the whole well thought-out. The best puzzle was the secrety who was stealing company secrets by typing memos in such a way that her key strokes were Morse code translations of the memos she was typing. Awesome!!
These stories are written for grade schoolers, and are entertaining & thought-provoking. Interestingly enough, Futrelle went down with the Titanic. Lost with him were several unpublished Thinking Machine stories.