Several methods of measuring the wave-length of electric waves on wires have been investigated. It was found that incorrect results were obtained when neon glow-tubes were moved along the wires to indicate the voltage nodes. By placing the neon lamp at the far end of the wires, however, and using shorting bridges to indicate the nodes, it was found possible to obtain quite consistent results. A thermogalvanometer, used in a similar manner, proved to be a somewhat better indicator and gave results which were more precise.