Platinum Temperatures. 



451 



Nos. 5, 11, 13 less trustworthy than the remaining twelve. 

 These twelve are given in Table I. In this table the 1st 

 column is the number of Professor Callendar's observation 

 as given in his table A.-v. ; the 2nd and 3rd columns are 

 the corresponding Centigrade and platinum temperatures 

 respectively, also from table A.-v. ; the 4th column contains 



Table I. 



(1) 



(2) 



(3) 

 572°9 



(4) 



(5) 



(6) 



(7) 



(8) 



14 



624°2 



19674 



57-933 



57-936 



57-935 



steady. 



31 



599-8 



552-6 



19-668 



56-558 



56-563 



56-56 



2-75 



24 



532-2 



4960 



19-668 



52-805 



52-784 



52-795 



steady. 



30 



440-9 



4171 



19-668 



47516 



47517 



47-52 



T2 * 



12 



39V8 



373-5 



19674 



44-619 



44-619 



44-62 



2-12 



6 



360-9 



345-8 



19-674 





42-769 



42-77 



0-43 



23 



288-7 



280-6 



19668 



38-416 



38-403 



3841 



3-23 



7 



278-4 



270-9 



19-674 



37-770 



37-767 



37-77 



steady. 



10 



259-5 



2533 



19-674 



36-602 



36-591 



36-60 



steady. 



9 



255-5 



249-5 



19674 



36342 



36-337 



36-34 



300 



35 



232 90 



228-08 



19-668 



34-894 



34-896 



34-895 



steady. 



36 



225-71 



221-14 



19-668 



34427 



34 433 



34-43 



steady. 



the values of R which he used in calculating tzr; the 7 th 

 column is the resistance of the platinum wire from which zr 

 was obtained, taken as the mean of columns 5 and 6 ; the 8th 

 column indicates the steadiness of the temperature during 

 each experiment. The 7th column was obtained from Pro- 

 fessor Calendar's numbers in two ways; (1) by going through 

 the process exemplified at the foot of p. 218 of (Call.), and 

 (2) by calculating backwards from the formula, p. 218 of 

 (Call.), _ E/R -i 



OT -0033947' 



the two processes giving respectively the 5th and 6th columns, 

 of which the 7th column was the mean. In the 8th column 

 an experiment was considered to be at steady temperature 

 when the observed resistances of the spiral sometimes increased 

 and sometimes decreased. In the case of a varying tempera- 

 ture the number in this column is the number of hundredths 

 of an ohm by which the final observation in the set exceeded 

 or fell short of the first observation in the set, divided by the 

 number of minutes during which the set lasted. 



These twelve observations were carefully plotted, and I 

 finally employed the numbers in Table II., columns 2 and 3, 

 from which to construct a formula connecting temperature 

 and resistance for this particular wire. 



