436 Procecdiiiya of the Royal Dublin Society. 



1485 grammes ; while the latter, F, weighs only 437 grammes. 

 In this instance the lower note is about three and a-quarter times 

 the weight of the higher. Many other incongruities could be 

 shown, did space permit. 



The ringing quality of the stone depends on its jpoints of sus- 

 pension. Of course there are lines of vibration in the stone, and 

 in these lines are nodal points, or points of no vibration. It is at 

 these points the stone must be supported, otherwise the support 

 will greatly interfere with the ring of the note. A stand con- 

 structed to meet this would be a most complicated one. Besides 

 that, it must be so long that the walking exercise of scale playing 

 would be so very exhausting as to entirely overcome tli^ pleasure 

 derivable from the otherwise entrancing performance. 



Some of these stones give out a double sound ; the lowest, for 

 example, when struck, sounds A flat and E natural — a minor 

 sixth. But I will merely draw your attention to two. First, 

 No. 7 produces G and B flat — a minor third ; the whitened part 

 of the stone gives Gr, and the points which give the most distinct 

 B flat are reddened. The other is No. 10. This is C, producing 

 also D — a full tone. The C-producing part is white, and the D-, 

 where clearest, blue. You will observe that these stones have four 

 points (marked with black dots on the white ground) diametrically 

 opposite each other, which give the true note of the stone, while 

 between each of these is a spot where the false note is given very 

 clearly ; and in the centre, where the lines of vibration cross, it is 

 impossible to get either note true. 



In conclusion, this Eock Harmonicon is an effective musical 

 instrument, made of limestone in its natural condition; contains 

 some stones which produce double sounds — some in sixths, some in 

 thirds, some in seconds. That such sets are not common may be 

 gathered from the fact that so little information is to be had con- 

 eerning them. 



