THE HARMONOGRAPH. 



77 



From the point of view of acoustics it constitutes a less curious object of 

 study. The experiments of M. Lissajons have proved that the vibrations 

 of diapasons are oscillations similar to, though much more rapid than those 



Fig. 177. Ratio i : 2. Fig. 178. Ratio 2 : 3. 



of the pendulum. We can therefore with this apparatus reproduce all the 

 experiments of M. Lissajons, with this difference, that the movements being 

 slower are easier to study. When the ratio between the number of vibrations 



Fig. 179. Ratio i : 2 and a fraction. 



Fig. 1 80. 



Fig. i8x 



Construction of the Harmonograph. 



we purposely use the term vibration instead of the term oscillation is a 

 whole number, we obtain figs. 177 and 178. If the ratio is not exact, we 

 obtain fig. 1 79, which is rather irregular in appearance, corresponding to the 



T2 



