126 Mr. Tomlinsoiis Experiments and [Aug. 



carried round in a direction contrary to the finger (39). 

 I then produced the secondary tone C sharp within the 

 stave, and the mercury, the shots and the wire, were alto- 

 gether quiescent, while the water without the glass was in 

 a state of active vibration. 



64. It must not be imagined that the secondary tones 

 are faint and almost inarticulate, nor that they are pro- 

 duced by partial vibration of the upper edge of the glass 

 alone ; on the contrary, they are nearly as strong and quite 

 as clear as the fundamental note of the glass. If the ends 

 of the fingers be placed on the exterior surface of the glass, 

 active vibration is immediately appreciated ; whereas, when 

 the glass yields the fundamental note, the hand may be 

 placed round the exterior of the glass ^ in any part, or a 

 cloth may be folded round it without altering the note, or 

 sensibly diminishing the vibration of a fluid within ; the 

 clearness of the note, however, is somewhat diminished 

 (21). The glass may also be filled with water within a 

 quarter of an inch of the edge, and the fundamental and 

 secondary tones produced with the same vibrating and non- 

 vibrating results as respects the fluid or liquid contents of 

 the vessel : but the terms positive and negative states of 

 vibration, are, of course, only to be understood in relation 

 to each other ; for during the production of the fundamental 

 note, both the interior and exterior of the glass vibrate 

 and the hand is sensible of the vibration, though I do not 

 believe the partial vibration of the exterior surface to affect 

 the production of the real fundamental tone. 



65. It will be understood, that in speaking of the funda- 

 mental tone of a glass, I intend that tone produced under 

 ordinary circumstances from a musical glass, when mercury 

 or water, &:c. within such glass vibrates readily. Strictly, 

 the real fundamental tone is produced when the glass con- 

 tains only air, and such a tone is superior to any other that 

 may be produced by the addition of liquids, (51). The 

 secondary tones can be produced whatever may be the con- 

 tents of the glass ; and the effect is peculiary novel and 

 pleasing, when a single glass is employed containing either 

 mercury, water, or liquids that will vibrate (23), and whose 

 specific gravity is less than that of water (59). By practice 

 I have attained considerable facility in bringing out the 



• Vide (21.) for " inside " read " outside." 



