This luxurious pipe of the Orientals is simple in construction. though often made of the most expensive materials. It is, however, generally composed of a red-clay bowl and a cherry stick stem. It washes the smoke precisely as gases are washed in the chemical laboratory, by passing them through water. It not only washes but condenses a great portion of the essential oil which would otherwise pass into the mouth with the smoke. This oil contains nicotine, a deadly poison , and the active principle of tobacco ; therefore the use of pipes of this kind is not so injurious as that of ordinary pipes. Its operation is as follows : The upper part of the bowl contains the tobacco, and a tube runs from it into the lower part, which is half filled with water. When the air is exhausted by “ drawing” through the pipe, the smoke rushes down the tube and escapes through the water. THE velocity of light is so enormous, about 185,000 miles per second, that it can readily be imagined that any motion which we can experimentally produce in a source of light is at rest in comparison.