These are the blades I tested as detectors for foxhole radios. These are all in black and white in the book so here they are presented in glorious color.
Captions are from the book.
(Above) Blades tested as detectors. From top left: WWII era Blu-Strike, Club, and Durex; a military issue Gem single edge plain steel blade; a Gillette “Blue” blade; a military issued Gillette blade in camouflage wrapper; an early 1920s Gillette blade; an early 1960s Gillette “Super Blue” blade; a WWII era Gillette “Thin” blade. More blades tested as detectors. From top left: a WWII era Gilt Edge; a Marlin “High Speed” with 1s and 2s in the corners, similar to the one used in Paul Cornell’s radio; a civilian “High Speed” blade (note that the Marlin “High Speed” blades have the same center slot design as the Blue Strike and Durex blades in the previous photograph and likely were made by the same manufacturer); Marlin blade with an oval slot design; two versions of the Marlin “Perfect Edge” military issue blade in camouflage wrappers; the civilian version of the Marlin “Perfect Edge” blade with yet another slot design; a contemporary stainless Gillette Wilkinson blade; WWII era Pal and Star blades.
