507 



lysed, the oxide of iron is in greater quantity than the alumina; while 

 in all the analyses of this pottery I have seen, the alumina is the 

 greater. 



The specimen of this ware which I analysed was procured from 

 the Museum of the Society of Antiquaries, Edinburgh, 



After the analysis of the mass of this pottery was finished, I 

 scraped several of the pieces at my disposal, so as to ascertain the 

 composition of the glaze of this beautiful ware. I could only procure 

 enough for a qualitative analysis ; but this was sufficient to show a 

 circumstance already noticed about this pottery, namely, that its 

 glaze contains no tin, lead, or antimony, or any of the heavy 

 metals. 



100-21 



G. Theory of Linear Vibrations. Part VI. AUigated 

 Vibrations. By Edward Sang. 



This part of the paper contains an inquiry into the action of a 

 vibrating body upon a linear elastic series, as representative of the 

 action of a sound-emitting substance upon the air. 



It results that when one end of a linear elastic series is attached 

 to an oscillating substance, all the internal oscillations of which the 

 system is capable when one end of it is fixed, are called into exist- 

 ence ; the number of these being equal to the number of the ele- 

 ments in the system, and their periodic times being mutually incom- 

 mensurable; and that to these is added another, isochronous and 

 synchronous with that of the oscillating substance. 



The investigation shows that the whole of these oscillations are 

 instantaneously communicated to the system, and that the state of 

 repose in which it was at first is merely that phase of the general 

 motion in which all the parts but one have their velocities simul- 

 taneously zero. 



