1895-96.] Dr Beattie on Thermo-electricity in Bismuth. 151 
Plate I . — Magnetic Field about 3000 e.g.s. units. 
Plate I. 
Plate II. 
Temperature in 
Hall effect propor- 
Temperature 
Hall effect propor- 
deg. C. 
tional to 
in deg. C. 
tional to 
- 74 
1*256 
- 69 
0*866 
- 72 
1*250 
- 64 
0*889 
- 65-5 
1*245 
- 59 
0*915 
- 58-5 
1*246 
- 51 
0*970 
- 52-5 
1*244 
- 47 
0*985 
- 47-5 
1*241 
- 41*5 
1*007 
- 40*5 
1*211 
- 35*5 
1*016 
- 36 
1*211 
- 31*5 
1*030 
- 27-5 
1*190 
- 25 
1*032 
- 23-0 
1*180 
- 19*5 
1*034 
- 14 
1*139 
- 12*0 
1*040 
- 7*5 
1*110 
- 8 
1*034 
0 
1*056 
- 4 
1*034 
+ 7 
1*050 
+ 0*5 
1*034 
+ 11 
1*046 
+ 7*5 
1*034 
+ 21 
1*000 
+ 21*5 
1*028 
+ 43-5 
0*927 
+ 26*5 
0*980 
+ 76 
0*784 
+ 56*5 
0*869 
+ 93 
0*700 
+ 84*5 
0*725 
+ 95 
0*697 
+ 105*0 
0*634 
+ 124 
0*532 
+ 124*5 
0*540 
+ 157*5 
0*411 
+ 152*0 
0*729 
+ 198*5 
0*313 
+ 203 
0*288 
+ 246*5 
0*280 
+ 219*0 
0*217 
+ 242*5 
0*175 
The numbers given for Hall effect are expressed in terms of the 
effect for the plate considered at 21° C. 
The general features of the two pairs of curves are almost exactly 
similar. In Lebret’s plate I., there is a maximum at about - 74° C., 
and in his second plate a maximum at about - 20° C. On the 
other hand, in Dewar and Fleming’s two specimens of commercial 
bismuth the curve of thermo-electric force has for plate 1 a maxi- 
mum value at about - 43° C., for plate 2 a maximum at about 
- 81° C. 
If we denote the numerical value of the transverse effect by E : 
then E can be expressed as a parabolic function of the tempera- 
ture ; using Lebret’s figures we can for Plate II. put 
- E = at + bt 2 
where a and b are constants + 0*00859 and ± 0 '00001 7 9 respectively 
