Lecture Experiments on the Nodes of a Bell

Abstract

I WAS much interested in the communication from Mr. Osborn on the above subject (see NATURE, January 9). For some years I have been in the habit of showing these nodes in the following way. An ordinary glass bell-jar, eight or ten inches high, with a moderately broad, flat, ground edge, is held with the edge upright, and fine sand scattered all over the flat edge. It is comparatively easy to excite the edge with a bow in such a way that the sand will be driven off everywhere except at the four nodes. I have never been able, however, to obtain more than four nodes in this way.