This electromagnetic wave detector consists of a small glass tube similar to a fuse containing tiny iron filings. These filings are attracted by the coherer wire during the passage of radio waves. This attraction and repulsion of the filings – during a short or slightly longer period – operates similarly to Morse short (also known as dots) and longer (also known as dashes) signals. The base is rectangular and made of wood. On the top, at each side, is a metal terminal to which are attached the earpiece conductors. On the lower section of the upper surface is a set of electrical components that make up the reception circuit, i.e. a switch that can be moved across a 90º angle to increase or reduce the reception resistance, three metal terminals to connect to exterior resistances, a Branly coherer to indicate the voltage, and an electrical lead with a terminal connector to select different reception positions.