1896.] Mr Griffiths, On Thermomebric "Fixed Points." 231 



Results of Boiling Point determinations, Oct. 7, 1896. 



It thus appears that our present definition is sufficient from a 

 practical standpoint for, since there is no lag, the same conditions 

 can be reproduced by different observers with sufficient accuracy 



and, further, Regnault's values of -y- are, for pressures near 760, 



sufficiently accurate. From a theoretical point of view, however, 

 the conditions are by no means perfect. We require a standard 

 absolute pressure, the value of which can be stated without our 

 present arbitrary method of reference to a mercury column, and it 

 seems fitting that the attention of physicists should now be directed 

 to this question. The effects of any change, however, would be so 

 far-reaching that I doubt if I should have ventured to express my 

 own views on this matter had it not been for the powerful support 

 afforded by a letter I have recently received from Professor Hicks, 

 F.R.S., of Sheffield. He has been so kind as to give me per- 

 mission to make what use I please of that letter, and I cannot 

 close this communication better than by transcribing it almost in 

 full. 



