At a recent meeting of the Boston Society of Natural History, as reported in the Traveler, Wm..Edwards, of South fratick, Mass., read a paper on the above subject, which effectually disposed of air behind the falling sheet of water, as some have supposed, being the cause of these vibrations. During the month of December, he made experiments on the dam at South Natick, where the vibrations are sometimes very violent. He erected a short flash-board on the top of the dam, at the one side, so that he could walk dry behind the sheet of falling water. Having been a believer in the theory of air causing the vibrations, he expected to find a violent wind under the sheet, but behold it was so calm that a feather descended as quietly as in a room, and the flame of a lamp was scarcely ruffled. He found the water as it fell to assume the spheroidal form, as before set forth in our columns, thus causing the vibrations.