144 K R. Hall— Effect of Magnetic Force on the 



A = mean Teading of ammeter during observations on transverse 

 current. These readings may for our purpose be consid- 

 ered as giving the strength of the magnet current in am- 

 peres. This probably understates the current somewhat. 

 A' = same during measurement of intensity of magnetic field 



by means of test-coil. 

 R = change of reading on scale of ballistic galvanometer pro- 

 duced by induction current from loop on cross. The num- 

 ber of such divisions corresponding to 1° of actual deflection 

 is about 3'6. 

 M. F. = same produced by induction current from test-coil on 

 being pulled out from magnetic field. These readings re- 

 duced to correspond with E. I. at 7.6 and then multiplied by 

 1000 give approximately the intensity of the magnetic field 

 in absolute, c. g. s. units. 

 E. I. = same produced by earth inductor in circuit with test-coil 



and loop on cross. 

 D == movement from extreme to extreme of spot of light on 

 scale of astatic galvanometer used to measure transverse 

 current from cross. 1° actual deflection = about 3*6 divi- 

 sions on this scale. 

 6 = reading of tangent galvanometer measuring direct current 

 through cross. Reduction factor of this galvanometer = 

 about 0*3. Hence direct current = about 2 amperes. 

 t — temperature of astatic galvanometer circuit. 

 t' = temperature of cross. 



No. 5. 

 A R D 6 



June 4, 1888* j 24'75 5*05 9*255 35° 46' 

 June 5. I 26-30 4-65 8-770 36° 37' 



Mean. 

 June 8. 

 June 8. 



Mean. 24-8 4-95 9-01 36° 26' 7-70 16*27 23'6 29 24 



Reducing the two means to uniform conditions by methods 

 self-evident or already indicated, we find 



B.I. 



M. F. 



A' t 



*' 



7-58 



16-47 



23-75 27 



30 



7-56 



16-83 



25-50 27 



22 



25-5 

 f 24-4 

 j 25-1 



4-85 

 4-96 

 4-93 



9-01 

 8 71 

 9-30 



36° 12' 

 36° 23' 

 36° 28' 



7-57 

 7-70 

 7-70 



. 16-65 

 16-27 



16-27 



24-6 

 23-2 

 24-0 



27 26 

 29 20 

 29J 28 





A 



R 



D 



e 





E. I. 



M. F. 



A' 



t 



V 



June 4 and 5. 



25 



4-84 



9-06 



36° 





7-60 



16-18 



25 



25 



28 



June 8. 



25 



4-89 



9-22 



36° 





7-60 



16-20 



25 



25 



28 



Mean. 



25 



4-87 



9-14. 

 Nc 



36° 



». 7. 





7-60 



16-5 



25 



25 



28 





A 



R 



D 





e 



E. I. 



M. F. 



A' 



t 



t' 



June 4. 



j 25-2 

 I 25-1 



6-84 



1-955 



36° 



47' 



7-68 



16-52 



23-35 



24° 



24° 



June 5. 



656 



1-975 



37° 



57' 



7-68 



16-65 



24-03 



29° 



31° 



Mean. 



25-15 



6-70 



1-970 



37° 



22' 



7-68 



16-59 



23-69 



26£ 27£ 



June 7. 



j 23-92 

 | 24-4 



6-35 



2-05 



37° 



25' 



7-74 



1654 



23-50 



29 



26 



June 7. 



6-36 



1-70 



37° 



13' 



7-82 



16-64 



23-60 



30 



31 



Mean. 



24-16 



636 



1-875 



37° 



19' 



7-78 



1.6-59 



23-55 



29£ 28£ 



* The -{ embraces complementary sets. 



