Rowland's Thermometers with the Paris Standard. 



comparisons were made at successively higher temperatures. 

 In order to reduce the readings of his thermometers to the 

 air-thermometer, Rowland found by calibration the apparent 

 volume occupied by the mercury corresponding to each 

 division-line on the stem. He assumed that the temperature 

 on the air-thermometer was a function of the second degree 

 of this volume. He made a number of comparisons between 

 his thermometers and the air-thermometer, and, by the 

 method of least squares, found the equation connecting the 

 temperature and volume. From this he constructed a table 

 for each thermometer giving the air-thermometer temperature 

 corresponding to each centimetre on the stem. These tables 

 are given on pp. 115-116 of his paper on the mechanical 

 equivalent, and are reproduced here in Table II. The correc- 

 tions to reduce the air-thermometer temperature to the absolute 

 scale are deduced from the experiments of Thomson and Joule, 

 and are given here as Rowland gives them on p. 114 of his 

 paper (Table III.). 



Table II. 



Reduction of Rowland's Baudin thermometers to the air- 

 thermometer, and to the absolute scale. (From p. 115 of 

 Rowland's paper on the mechanical equivalent of heat.) 



Column A.. Heading in centimetres on the stem. 

 Column B. Temperature on the air-thermometer. 

 Column C. Temperature on the absolute scale. 



Baudin 6163. 



A. 



B. 



C. 



A. 



B. 



C. 



5 



-0°911 



-0°911 



24 



20-350 



20-345 



5-81 











25 



21-457 



21-452 



6 



+0214 



+0-214 



26 



22-559 



22-554 



7 



1-328 



1-328 



27 



23-657 



23-652 



8 



2-461 



2-460 



28 



24-755 



24-750 



9 



3-584 



3-583 



29 



25-854 



25-848 



10 



4-707 



4-706 



30 



26-956 



26950 



11 



5-829 



5-827 



31 



28-060 



28-056 



12 



6950 



6-948 



32 



29169 



29-163 



13 



8-071 



8-069 



33 



30-282 



30-276 



14 



9-193 



9-190 



34 



31-398 



31-392 



15 



10-314 



10-311 



35 



32-514 



32-508 



16 



11-435 



11-432 



36 



33-630 



33624 



17 



12-556 



12-553 



37 



34-748 



34742 



18 



13676 



13672 



38 



35-864 



35-857 



19 



14-794 



14-790 



39 



36979 



36-972 



20 



15909 



15-905 



40 



38-094 



38087 



21 



17-022 



17-018 



41 



39-206 



39199 



22 



18-132 



18127 



42 



40-316 



40-309 



23 



19-242 



19-237 





1 





