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Experimental Researches regarding certain Vibrations which take 

 place between Metallic Masses having different Temperatures. 

 By JAMES D. FORBES, Esq. F.R.SS. L. & E., Professor of 

 Natural Philosophy in the University of Edinburgh. 



(Read 18th March and 1st April 1833.) 



1. ON the 17th January 1831, Mr ARTHUR TREVELYAN com- 

 municated to the Royal Society of Edinburgh a paper, entitled 

 " Notice regarding some phenomena observed during the Cool- 

 ing of certain Metals placed in contact with Lead." This was 

 the first account published of the remarkable discovery made by 

 that gentleman, of a most curious class of phenomena, which till 

 then was unknown to the scientific world. This paper was after- 

 wards published, with some additions, in the 12th volume of the 

 Transactions of that body, under the title of " Notice regarding 

 some Observations on the Vibrations of Heated Metals." 



2. Mr TREVELYAN had, in February 1829, first observed the 

 phenomena just alluded to, which consist in certain tremulous 

 motions accompanied by sounds, often highly musical, excited in 

 many metals while hot, placed in contact with lead or tin, at a 

 lower temperature. The method of rendering these conspicuous 

 will be understood from Plate X. Fig. 1, where A represents a 

 block of lead, and B a bar of some other metal, such as brass 

 or copper, which is made of such a form as to vibrate readily 

 upon two points of support, formed by the solid angles of a ridge 



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