It has also been proposed to use the microphone to give notice of an escape of gas in coal-mines. The gas, in escaping from between the seams of coal, makes a whistling noise, which might, with the aid of the microphone and telephone, be heard at the top of the shaft. Again, it has been suggested that the microphone might be used as a seismograph to reveal the subterranean noises which generally precede earthquakes and volcanic eruptions, and which would be much intensified by this instrument. It might even be of use to Signor Palmieri for his observations in the Vesuvius Observatory. The microphone has also been used by Mr. Chandler Roberts to render the diffusion of gaseous molecules through a porous membrane sensible to the ear. As might have been expected, the acclamation with which Mr. Hughes’s invention was received led to the assertion of other claims to priority, and in addition to that of Mr. Edison, on which we have already given our opinion, there are several others, showing that if some microphonic effects were discovered at different times before the date of Mr. Hughes’s discovery, they could not have been considered important, since they were not even announced. Among the number was that of Mr. Wentworth Lascelles Scott, specified in the ‘Electrician’ of May 25, 1878, and that of M. Weyher, presented to the Société de Physique, Paris, in June 1878. Another, made by M. Dutertre, is of somewhat greater importance, for his experiments were reported in the Rouen papers in February of the same year: yet there is no just ground for such claims, since the earliest date of his experiments is subsequent to the experiments first made by Mr. Hughes. These began early in December 1877, and in January 1878 they were exhibited to officials of the Submarine Telegraph Company, as Mr. Preece declared in a letter addressed to the several scientific men. EXTERNAL INFLUENCE ON TELEPHONIC TRANSMISSIONS.