THE following experiments were suggested by the description, which appeared in a recent number of NATURE, of the microphone lately invented by Professor Hughes. Instead of the pointed piece of carbon supported between two pieces of the same material as used by him, it occurred to me that ordinary gas cinders would be likely to answer the purpose tolerably well. To test this, I included in the circuit of an ordinary Bell telephone, a single Leclanchè cell, and a small jelly can half filled with cinders broken into pretty coarse fragments. The connections were made by slipping down at opposite sides, between the cinders and the sides of the jar, two strips of tin, to which the circuit wires were attached. When the simple instrument was used as a transmitter, articulate sounds were heard very loud and distinct in the distant telephone, though occasionally marred by what appeared to be the rattling of the cinders in the jar. With this transmitter sounds were also quite audible, even when the speaker stood several yards away from it.