Researching foxhole radios and early radio wave detectors uncovers a lot of clever and strange equipment improvised by early radio amateurs. Like this radio wave detector made from a potato from the July 1915 issue of The Electrical Experimenter, invented by Milton Rochkind. As he explains it:

While putting up an aerial in my yard (80 feet long and 60 feet high) recently I tried to receive wireless messages. I took a potato and placed it on a box. Then I took two sewing needles. I took one needle and stuck it into one side of the potato. I then connected the second needle with one pole of the receiver and stuck it in the other end of the potato. I took the ground wire and connected it with the other end of the pole of the receiver, and when this was completed I was able to receive many messages just as clearly as from a detector.

The editor assumed the potato was acting like an electrolytic detector, a common detector of the era. I tried repeating the experiment but never got a signal. If anyone reading this manages to make a working radio from a potato I would love to hear about it. 

There were an amazing variety of radio wave detectors in the pre-crystal and vacuum tube days. They are well covered in Vivian J. Phillips’ Early Radio Wave Detectors. Stevenage, Hertfordshire, England: P. Peregrinus in association with the Science Museum, London, 1980.