The Vibrations of Quartz Plates

By vibrating quartz crystals in an electric circuit Wright and Stuart have shown that the crystals break up into different parts while oscillating. The nodal lines thus formed are made visible to the eye by lycopodium powder. In the present paper it is pointed out that the mathematical theory of Chladni plates gives a general equation, A cos-cos -+ Bcos --cos = 0, for the nodal lines of square plates. This equation is also applicable to quartz plates in so far as the forms of the nodal lines are concerned. It gives no information regarding the manner of vibration of the quartz. Chladni plates both square and round have been vibrated by mechanical impact from a vacuum tube oscillator circuit. A few of the figures thus obtained are shown and may be compared with those of Wright and Stuart. The nodal lines for circular quartz plates do not in general resemble those of circular Chladni plates.