80 



Mr. W. C. Baker on the Hall Effect in 



Another sheet of similar dimensions with t = l'lZx 10 -4 * 

 gave the same values for the Hall coefficient. 



The results of a series of measurements on a sheet of 

 dentists' gold, from a " book " marked " Chemically Pure 

 Gold, soft extracohesive No. 4," are given in the following- 

 table, where, in the first column, is recorded the date of the 

 observation. In the second column, marked H, is given the 

 magnetic field-strength in C.G.s. units. The third column, 

 marked /3', gives numbers proportional to the Hall co- 

 efficient f, and the fourth column gives the strength of the 

 current (in amperes) that flowed through the secondary 

 system due to the Hall effect. These latter values are cal- 

 culated from the formula 



2 VR, RV <,,' 



and are used in the diagram (fig. 3, p. 82), where they are 

 plotted against the corresponding field-strengths. 



Table I. 



Date, 

 1901. 



H. 



(C.G.S.) 



/3\ 



Current in 



Secondary due to 



Hall eftect 



(amperes). 



May 



8 



7 



6 



7 



8 



6 



8 



7 



6 



8...... 



7 



30 



23 



23 



31 



12-6 

 12-8 

 131 



24-5 

 24-6 

 25 



69-5 

 700 

 71-7 



94-5 

 95-0 

 97-0 



151 

 151 

 151 

 153 



4-9x10-4 



4-9 



48 



50 



5-4 

 54 



5-4 

 52 

 5-2 



5 2 

 5-2 

 51 



5-7 

 5-6 

 5-6 

 53 



12-8x10-9 



12-8 



12-8 



25-2 



20-2 

 279 



773 

 74-9 

 772 



102 

 102 

 103 



172 

 174 

 173 

 1(58 



* The thickness of these sheets of dentists' gold varies from point to 

 point. For instance, the average value of t for the sheet used was 

 1-51x10— 4 cms., but the active central part, when cut out, thoroughly 

 cleaned and weighed, gave t= 2 05 X 10— 4 , 



f See explanation below. 



