Explore "The Technique of the Mystery Story" by Carolyn Wells on Textopian. Read with annotations and highlights.
[Of the many devices introduced by detective writers to arrest and hold the readers' attention, some are admittedly legitimate and used by best authors. Others are unfair; and still others were permissible but have become so hackneyed as to be taboo.]
In "Monsieur Lecoq" much depends on the footprints in the snow. Thereafter in the first chapter of nearly every detective story we are informed that "a light snow had fallen the evening before." Then witnesses are brought to prove the exact hour the snow began to fall, and the moment it stopped. This fixes the time of the murder, and the footprints in the snow lead to or from the criminal as the author may decree.