1890.] Dr Gamgee, On Fahrenheit's Thermometrical Scale. 95 



iu altering the pitch of several of the notes of lowest pitch, and 

 other tables show the numerical magnitude of the corresponding 

 maximum changes of pitch. 



The changes in the types of vibration in solid spheres or 

 cylinders due to the existence of thin intercalated layers of other 

 media are determined by a different method. This method also 

 leads to expressions for the changes of frequency in these systems 

 which are identical with those obtained by the first method. 



The results obtained in the memoir are very numerous, and 

 many of them seem of interest from a physical point of view. 

 They show that general laws as to the effects of altering the 

 stiffness or elasticity of vibrating systems unless carefully restricted 

 may lead to very erroneous conclusions. 



November 10, 1890. 



Professor G. H. Darwin, President, in the chair. 



The following Communications were made to the Society : 



(1) Note on the principle upon which Fahrenheit constructed 

 his Thermometrical Scale. By Arthur Gamgee, M.D., F.R.S., 

 Emeritus Professor of Physiology in the Owens College (Victoria 

 University). 



[Abstract; reprinted from the Cambridge University Reporter, Nov. 18, 1890.] 



The author commenced by drawing attention to the fact that, 

 although the Fahrenheit thermometer has been so generally used 

 in England, no accurate information was to be found in our text- 

 books concerning the principles upon which its scale had originally 

 been constructed. He referred, however, to a view advanced by 

 Professor P. G. Tait in his elementary treatise on 'Heat,' and 

 which had been accepted by many teachers, according to which 

 Fahrenheit divided his scale between 32° and 212° into 180 de- 

 grees, in imitation of the division of a semi-circle into 180 degrees 

 of arc. This theory rested on the incorrect supposition that, before 

 Fahrenheit's time, Newton had suggested, as a basis for a thermo- 

 metric scale, the fixing of the freezing and boiling points of water, 

 the space between these being divided into a number of equal 

 degrees. The author pointed out that in his " Scala graduum 

 caloris," Newton made no such suggestion as that attributed to him 

 by Professor Tait, and prior to him by Professor Clerk Maxwell ; and, 

 indeed, that Fahrenheit had settled the basis of his scale and had 

 constructed a large number of thermometers which were used by 

 scientific men throughout Europe, many years before the discovery 

 by Amanton (which Fahrenheit confirmed and gave precision to) 



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