After the discovery new waves by
Heinrich Hertz, Threlfall suggested in a 1890 oral discussion that "Signaling, for instance, might be accomplished secretly by means of a sort of electric ray flasher", thus predicting yet-uninvented
radio communications. In July 1915 he invented the 'Threlfallite'
hand grenade, consisting of a cylindrical tin containing white phosphorus, paraffin, oil and petrol. Originally designed as an incendiary device to destroy long grass in front of the trenches that gave cover to enemy raiding parties, it also had a useful smoke-producing effect and was used at the
Battle of Loos. == Death ==