540 MR A. CRICHTON MITCHELL ON THE THERMAL CONDUCTIVITY 









CoiTCC 



;ion at 





Kew 

 Standard, 



No. 



Range Centig. 











o°c. 



ioo° c. 



200° C. 



350° C. 



*431 



U -100° 



o-o 



-01 







432 



0°-100° 



o-o 



-01 









433 



0°-100° 



00 



00 









434 



0°-100° 



00 



00 









435 



0°-100° 



00 



+ 0T 









43G 



0" - 200° 



o-o 



00 



o-o 







437 



0° - 200 J 



00 



+ 02 



+ 01 







438 



0°-200° 



00 



+o-i 



+ 0-1 







439 



0°-200° 



00 



00 



00 







440 



0°-200° 



00 



+ 0-2 



+ 0T 







441 



0°-350° 



00 



+ 015 



+ 01 







*442 



0°-350° 



00 



+ 015 



+ 0-25 







443 



0°-350° 



00 



+ 01 



+ 0-25 







444 



0°-350° 



o-o 



+ 0-25 





+ 0-3 



*445 



0°-350° 



-01 



-01 





+ 0T 



446 



0°-350° 



00 



+ 0-2 





+ 0-3 



447 



0"-350 G 



00 



+ 015 





+ 01 



*449 



0°-350° 



00 



+ 01 





+ 01 



*450 



0°-350° 



00 



+ 005 





+ 0-05 



* Not used in the experiments. 



But after several exposures to high temperatures, sometimes nearly 300°, 

 the thermometers began to show an error, and that one of increase, in the 

 indications. The amount of this error in each instrument was found by 

 comparing the reading taken when the long bar had cooled down overnight 

 after the previous day's heating, with the simultaneous reading of a thermo- 

 meter in the short bar standing in the vicinity of the long bar. This latter 

 thermometer was only used for temperatures which did not exceed that of the 

 air, and had never been subjected to any such treatment as had those it was 

 employed to correct. The difference of the two readings named was taken as 

 the error of the first, and was applied in the reductiun of the experiments. In 

 tlie case of the thermometers used in the hottest hole in the bars, this error 

 amounted to about seven degrees at ordinary temperatures. 



A series of corrections for the different thermometers was thus obtained, and 

 in order to test whether the readings obtained from one day's work, and after 

 the application of these corrections, were consistent with those of another day, 

 the thermometers in the first three holes were interchanged among each other, 

 and also with the thermometer which was always used to indicate the temper- 

 ature in the cooling experiments on the short bar. It was found that the 

 different sets of readings when so tested were consistent with each other. 



This, however, is a source of less error than that which arises from the 

 circumstance that the temperature (especially at any point near the hot end) 

 of the long bar during an experiment is given by a thermometer with an 



