174 FE. H. Hall—New Action of Magnetism 
unknown, to which a has already been made. The re- 
sults obtained every day, except the last of my working with 
this plate, are so Hissdh det that in preparing ‘them for ‘publi- 
cation it does not seem worth while to go over again the great 
mass of figures involved, for the purpose of correcting any 
small errors of calculation. The results obtained were 
MxvVvV 
February 20th : = 134 XK 10” 
<< “ce - scoot 3 Lt aie eee 
“ 23d = ae LUD 6s 
6 “ce sp Ae ee 
“ “c és oe 160; 
““ 25th mat? Cae OO tes 
“ (4 6c as 1408 eS. 
«“ j “6 sc venti Oy Beer 
“ 27th eee. oe. 
“ “ Bes heme TAY foo ac. 
Mean “ = 152 x10’ 
Replacing now the old perforated poles of the electro-mag- 
net by solid new ones and removing one or two other sources 
of error, I found 
MxXV 
March 5th EO = 150 X 10” 
ce ia “6 a 150 : 
~ ey *) ee 156 : : ' 
Mean “ = 1513 X 10° 
The strength of thé magnetic field was, as usual, determined 
twice on March 5th, once before and once after the other ob- 
nt. The m 
strength for the day. The strength of the primary current 
sent through the gold strip was much varied for the different 
series of observation 
Thus we may Wife as corresponding to the above three 
values 
ge ae of Field. Strength of Joe Current. 
6400 kX jan! 23° 44’ 
4 ~ 42° 14 
“ “ce (74 49° 98’ 
when & is the constant of the tangent galyanometer = ‘07 
nearly. 
' The agreement between the mean of the various results pre- 
viously obtained and the mean of those found March 5th, was 
considered satisfactory, and the next measurements were made 
with 
