and Obsei'vations on Visible Vibration. 421 



and at the two points midway between. I then poured 

 coloured water into the dish, which reduced the notes to 

 B flat and D sharp : each of the notes produced four fans, 

 thus distinctly indicating a quadripartite division in each 

 case, and presenting the apparent anomaly of two funda- 

 mental notes from the same vessel. 



120. Analogy led me to suppose, that the secondary 

 tones would be doubled also ; that is, that I should get two 

 secondary tones due to sex-nodal division, each producing 

 six fans on the surface of the water ; two secondary tones 

 due to octo-nodal division, each producing eight fans, and 

 so on. I was not long in producing the first secondary 

 tone, which was D sharp in the second octave producing 

 six fans, and I also obtained another note G in the third 

 octave also producing six fans; thus, offering another 

 apparent anomaly of two first secondary tones. The D 

 sharp was produced at six equidistant points on the rim of 

 the basin including the lip, and the G was produced at six 

 other points midway between, and which did not include 

 the lip. I was not able to produce more than one octo- 

 nodal tone, the vessel not being sufficiently elastic, and the 

 lower notes tending to prevail. 



121. I then procured another wedgwood-ware basin, 

 and mounted it in a manner similar to the last. The 

 dimensions of this basin were larger, its diameter being 

 6J inches, and depth IJ inch. When empty, this vessel at 

 four points of the rim gave F, and at the other four points 

 B flat, both within the octave, shewing an interval of a 

 fifth. It also yielded two secondary tones, E and G, in the 

 first octave, thus shewing an interval of a third. Contain- 

 ing water, the two fundamental notes gave four fans each ; 

 and the two first secondary tones six fans each, and thus 

 the agreement with the former wedgwood-ware basin was 

 complete. 



122. I have submitted to experiment a great number of 

 tea cups, both of china and earthenware, and also common 

 blue cylindrical half pint cups, &c., and have always 

 obtained from each two fundamental notes, the interval 

 between which, has varied from a second to a fifth, and 

 where I have been able to get secondary tones of the first 

 kind due to sex-nodal division, I have always obtained two. 



