On a Practical Thermometric Standard. 

 L. Table VIIL— Weight of Quartz. 



519 



Date. 



1898. 



vni. 4. 



VIII. 4. 

 VIII. 5. 

 VIII. 5. 



Weight 

 in Air. 



3244750 

 58 

 60 

 53 



Temp 



19-0 

 19-35 

 18-0 

 18-4 



Bar. re 

 duced to 0°. 



762-25 

 762 04 

 75610 

 75605 



Weight of j Correction 



1 c. c. Dry i to reduce 



Air. to vacuo. 



00012123 

 12110 

 12067 

 12050 



+0-01016 

 5 

 1 

 



Corrected 

 Weight. 



32-45766 

 73 

 71 

 63 



W= 3245768 +0-000015. 



LVII. On a Practical Thermometric Standard. By H. L. 

 Callendak, M.A., F.R.S., Quain Professor of Physics, 

 University College, London*. 



WHEN I was invited to open a discussion on Platinum 

 Thermometry in Section A of the British Associa- 

 tion at Dover, it appeared to me that, in so wide a field, 

 the interest and utility of the discussion would be greatly 

 increased by proposing a definite text for the debate. I 

 accordingly drafted certain proposals for the adoption of the 

 platinum resistance-thermometer as a practical standard of 

 reference for scientific research. These proposals have been 

 printed and circulated, and are now in the hands of many 

 members of the section. They have also been submitted to 

 the Electrical Standards Committee, who, while giving 

 general approval to the scheme as a whole, have appointed a 

 sub-committee to consider details, and report progress next 

 year. 



The following is the text of the draft proposals : — 



'''Proposals for a Standard Scale of Temperature based on 

 the Platinum Resistance Thermometer. Drawn up by 

 Professor H. L. Callendar, M.A., F.R.S. 



" The following proposals are submitted in consideration 

 of the importance of adopting a practical thermometric 

 standard for the accurate verification and comparison of 

 scientific measurements of temperature. The gas-thermometer, 

 which has long been adopted as the theoretical standard, has 

 given results so discordant in the hands of different observers 

 at hio*h temperatures, as greatly to retard the progress of 

 research. 



* Communicated by the Author, having been read at the Dover 

 Meeting of the British Association. 



202 



