We have recently seen an article by Mr. Hughes in the ‘Telegraphic Journal,’ Nov. 15, 1878, in which, to our surprise, he not only opposes all the theories he has hitherto held, but cites experiments which are quite inconclusive, since they were performed under conditions in which electro-magnetic effects must necessarily be displayed. He made use of voltaic currents produced by a battery of three Daniell cells. In order to estimate the transverse effects resulting in such a case from attraction, the experiments he mentions are wholly unnecessary: they may be felt with the hand. On the other hand, he has evidently forgotten that the currents employed in a Bell telephone have no influence on a very sensitive galvanometer. _M. Pollard’s Microphone._--This microphone, which has been arranged in several ways, essentially consists of a carbon rod kept in a horizontal position by a wire, and resting on two other vertical carbons. The upright of the arm which holds the wire can revolve together with this arm, and is thus able to regulate the pressure of the horizontal carbon on the two vertical carbons. It appears that this instrument is extremely sensitive, and that the regulation effected on the two contacts is better than when it is effected on one only. It is fair to add that M. Voisin previously sent me the sketch of a somewhat similar arrangement. M. Dutertre has also made use of such an arrangement in what he calls the Dolmen microphone. Three pieces of coke in the form of a dolmen, that is, two uprights, supporting a third and horizontal carbon, are placed in circuit. M. Gouault has informed me that speech was well transmitted by this instrument, and it is, like that of Mr. Blyth, which succeeded it, of wonderful simplicity. This microphone, as well as one composed of two pieces of lead-pencil placed in a watch-case, and connected by a piece of money, were exhibited to the Industrial Society at Rouen, February 1, 1878, of which an account was published in the Bulletin of that society.