Violet ray machine
This handy kit became a staple in many homes around the turn of the 20th century. The Felma violet ray machine featured a shaft that contained a small Tesla coil, which sent high-voltage currents through these tubes. People would apply the tubes to their bodies to tone muscles, increase circulation, etc. This model was manufactured from 1930 to 1975 by Wissenschaftliche Apparate AG in Switzerland. Violet rays were ultimately banned because they produced ultraviolet light, which can damage the skin and produce ozone. The Bakken Museum still receives lots of offers to donate these devices, according to curator Adrian Fischer.