SOME CURIOUS FACTS CONCERNING HEARING.

An inquiry was recently made in London as to the greatest distance at which a man's voice could be heard, leaving, of course, the telephone out of consideration. The reply was most interesting, and was as follows: Eighteen miles is the longest distance on record at which a man's voice has been heard. This occurred in the Grand Cañon of the Colorado, where one man shouting the name "Bob" at one end his voice was plainly heard at the other end, which is eighteen miles away. Lieutenant Foster, on Parry's third arctic expedition, found that he could converse with a man across the harbor of Port Bowen, a distance of 6696 feet, or about one mile and a quarter: and Sir John Franklin said that he conversed with ease at a distance of more than a mile. Dr. Young records that at Gibraltar the human voice has been heard at a distance of ten miles.

Sound has remarkable force in water. Colladon, by experiments made in the Lake of Geneva, estimated that a bell submerged in the sea might be heard a distance of more than sixty miles. Franklin says that he heard the striking together of two stones in the water half a mile away. Over water or a surface of ice sound is propagated with great clearness and strength. Dr. Hutton relates that on a quiet part of the Thames near Chelsea he could hear a person read distinctly at the distance of 140 feet, while on the land the same could only be heard at 76 feet. Professor Tyndall, when on Mont Blanc, found the report of a pistol-shot no louder than the pop of a champagne bottle. Persons in a balloon can hear voices from the earth a long time after they themselves are inaudible to people below.