Temperature Coefficient or the Balance Magnet. 



xl 



111 



Taele 14. — Observations for the Temperature Coefficient of the Deflection Magnet. 



Gottingen 



Mean Time, 



1843. 



Tempera- 

 ture of 

 Magnet. 



to-t. 



Reading 



of 

 Unifilar. 



Reading 

 of Declino- 

 meter 

 reduced 

 = fd. 



M — Mo 



minus 

 f(d-do). 



Bifilar. 



Correction 



for r Fahr. 



= q. 



Reading 

 Corrected. 



Tliermo- 

 meter. 



d. h. m. 



Nov. 10 23 24' 

 23 53 

 Nov. 11 13 

 30 



46 



1 6 

 1 24 



1 42 



2 

 2 18 

 2 38 



2 54 



3 14 

 3 32 



3 53 



4 10 

 4 28 

 4 45 



Magnet 



35-30 



59-95 



76-85 



58-95 



36-90 



57-10 



78-70 



56-50 



36-60 



56-90 



81-95 



60-90 



36-85 



67-35 



43-95 



66-50 



Magnet 



away. 



24-65 

 16-90 

 17-90 

 22-05 

 20-20 

 21-60 

 22-20 

 19-90 

 20-30 

 25-05 

 21-05 

 24-05 

 30-50 

 23-40 

 22-55 



away. 



Sc. Div. 



264-39 

 10-73 

 1205 

 13-07 

 11-88 

 10-05 

 11-68 

 13-16 

 11-11 

 10-05 

 11-50 

 13-41 

 12-50 

 10-78 

 13-30 

 11-72 

 13-88 



264-35 



Sc. Di^. 



157-26 

 156-65 

 156-17 

 155-59 

 155-63 

 155-49 

 155-64 

 155-67 

 155-13 

 155-36 

 155-50 

 155-50 

 155-80 

 155-69 

 156-00 

 156-33 

 156-70 

 157-02 



Sc. Dir. 



1-80 

 1-60 

 1-23 

 1-69 

 1-48 

 1-45 

 1-51 

 1-29 

 1-31 

 1-91 

 1-21 

 1-61 

 2-21 

 1-91 

 1-79 



Sc. Dir. 



501-0 

 501-7 

 502-7 

 503-3 

 503-9 

 504-3 

 505-6 

 505-8 

 506-8 

 507-4 

 506-8 

 507-4 

 507-7 

 508-0 

 507-8 

 508-1 



42-6 

 42-7 

 42-8 

 42-9 

 43-0 

 43-2 

 43-6 

 43-8 

 43-9 

 44-0 

 44-3 

 44-6 

 44-8 

 44-9 

 45-0 

 45-0 



0-000287 

 •000369 

 •000278 

 •000309 

 -000289 

 •000260 

 •000272 

 •000265 

 •000253 

 •000307 

 •000233 

 •000268 

 •000287 

 •000324 

 •000315 



The mean value of ^ = 00002877. 



Balance Magnet. 



61. The value of the coefficient for the balance magnet was obtained by obser- 

 vations, similar to those for the deflecting magnet, on 5 difi'erent days ; weight was 

 given to the result of each day's observations, depending on the formula, No. 32. 

 The final result was 



q = 0-000073.* 



62. The impossibility of determining the value of the micrometer divisions of 

 the balance magnetometer by the usual method has been already pointed out. It 

 is obvious, therefore, that if shut up to this method the temperature corrections 

 cannot be applied even when the observations are left in the state of micrometer 

 divisions. The doubt whether the changes of the magnetic moment of the needle 

 occur as rapidly as those of temperature in all cases, and therefore, whether a co- 

 efficient obtained from changes of 30° or 40° in a few minutes (as in the tempera- 

 ture experiments) was likely to be applicable to observations where the changing 

 temperature of the needle was rarely above 1° in the hour, and the fact that other 

 sources of error (perhaps the effbct of temperature on the points of support of 'the 



Tables 19 and 20, Introduction to the Makerstoun Observations, 1841 and 1842. 



