"Don't throw the past away You might need it some rainy day." "Everything Old is New Again"
In the middle of longer piece on the mechanics of attrition in Ukraine, Big Serge describes a system for locating enemy artillery pieces called “Penicillin.” Like counter-battery radar, this device locates enemy artillery pieces when they fire. Unlike radar, which betrays its own position by emitting radio waves, Penicillin works without calling attention to itself.
For more on the sound-ranging systems of the First World War, see this splendid little film. For more on the ongoing war in Ukraine, read the entirety of the aforementioned article.
Note: The image at the top of this page comes from the draft of a technical manual found in a collection of documents about sound- and flash-ranging preserved in the German military archives.