Edison also furnished De Long with a set of telephones provided with extensible circuits, so that parties on the ice-floes could go long distances from the ship and still keep in communication with her. So far as the writers can ascertain this is the first example of "field telephony." Another nautical experiment that he made at this time, suggested probably by the requirements of the Arctic expedition, was a buoy that was floated in New York harbor, and which contained a small Edison dynamo and two or three incandescent lamps. The dynamo was driven by the wave or tide motion through intermediate mechanism, and thus the lamps were lit up from time to time, serving as signals. These were the prototypes of the lighted buoys which have since become familiar, as in the channel off Sandy Hook. One notable afternoon was that on which the New York board of aldermen took a special train out to Menlo Park to see the lighting system with its conductors underground in operation. The Edison Electric Illuminating Company was applying for a franchise, and the aldermen, for lack of scientific training and specific practical information, were very sceptical on the subject--as indeed they might well be. "Mr. Edison demonstrated personally the details and merits of the system to them. The voltage was increased to a higher pressure than usual, and all the incandescent lamps at Menlo Park did their best to win the approbation of the New York City fathers. After Edison had finished exhibiting all the good points of his system, he conducted his guests upstairs in the laboratory, where a long table was spread with the best things that one of the most prominent New York caterers could furnish. The laboratory witnessed high times that night, for all were in the best of humor, and many a bottle was drained in toasting the health of Edison and the aldermen." This was one of the extremely rare occasions on which Edison has addressed an audience; but the stake was worth the effort. The representatives of New York could with justice drink the health of the young inventor, whose system is one of the greatest boons the city has ever had conferred upon it.