I decided to go a bit farther with this. Chapter 3's subject matter is 'The Great Detectives', many of them created in the 1920s. I read three of the accompanying essays, which expand on the topic introduced in the previous chapter...so basically what we have here are essays on some fairly well-known books, overall. note: there are six more essays discussing individual books that give us "Great Detectives", but I'll leave them for later. interestingly, I have not heard of two of those six books--and so presumably I am completely unaware of the existence of two Great Detectives, which makes me wonder how Great they are, but Martin Edwards will get the chance to make a case for lesser-known Greatness.
of the three books I have just read about, courtesy of Edwards' assessments, I have actually sampled only one: The Mysterious Affair At Styles, which I very much enjoyed, long ago. I remember very clearly the crux of the solution...and how lousy it must be to die from strychnine poisoning! meanwhile, I have read other Peter Wimsey books, and been very happy with them. but I have not read his debut (NOTE/EDIT: I have made an error calling the book Wimsey's debut--see Comments section below! my bad!!), Clouds Of Witness; I must get to it. similar situation with the Anthony Gethryn series, by Philip MacDonald: I have not got to The Rasp, but I loved The Polferry Riddle. one of my favorite solutions to a Mystery (a rather creepy Mystery), that can be considered a bit "way out there" (call it tragic deaths, all from a horrible misunderstanding--a bit heart-wrenching, when finally revealed, actually). anyway, when I go into work and see the rasp beside all the other tools, I'm reminded I should, well, read The Rasp. you, however, should keep an eye out for The Polferry Riddle!
some tidbits of knowledge Martin Edwards passed along, or reminded me of: Agatha Christie had worked in a pharmacy, which helped her sort out using strychnine in her book; both Dorothy L. Sayers' and Philip MacDonald's Great Detective characters had both done Intelligence work against the Germans (spies, spiesspiesspiesspies!), so, new love and respect for Wimsey and Gethryn respectively. meanwhile, the taboo of injecting a love-interest into any series where the whodunit factor should quash such distractions became an outmoded, trampled taboo when authors gave in and started lovey-doveying things up even when they had pooh-poohed the idea earlier (here's looking at you, Sayers).