VERDET’S CONSTANT IN ABSOLUTE UNITS. 
29 
Ohs. 
Scale-readings in centims. 
Mean. 
1 . 
No torsion 
16-23 
16-23 
o 
Twist of 360°+ 
13-28 
13-36 
13-40 
13-40 
15-88 
15-85 
15-81 
15-80 
14-580 
14-605 
14-605 
14-600 
14-5975 
3. 
No torsion, viz. since (2) 
14-70 
14-70 
14-75 
14-75 
magnet turned 360° ( — ) 
17-90 
17-88 
17-80 
17-80 
16-30 
16-29 
16-275 
16-275 
16-2850 
4. 
Twist of 360°( — ) 
15-48 
15-50 
15-52 
15-53 
20-08 
20-04 
20-00 
20-00 
17*780 
17-770 
17-776 
17-765 
GO 
!>• 
5. 
No torsion, viz. since (4) 
13-70 
13-82 
13-90 
13-92 
magnet turned 360° + 
19-20 
19-10 
19-10 
19-04 
16-49 
16-46 
16-50 
16-48 
16-4825 
Mean zero from (1) and (3)=16-2575. From (2) this gives that 360° of twist+ 
causes a deflection corresponding to T660 centim. on the scale. 
Mean zero from (3) and (5)=16-3837, which from (4) gives a corresponding deflection 
of 1-385 centim. 
Mean deflection therefore =1*5225 centim. 
To obtain the number of minutes corresponding to this, we have the formula of 
(26), p. 16, 
tanw=i-— 
1 a ° cr 
where a=102-5 centims., and #=T5225 centim. 
This gives tan w=-0074251, 
which from the tables gives the angle in minutes by which the declination is changed 
by a twist of 360°, viz. 
w=25'*46 ; 
taking \ of this for the torsion produced by 90° of twist we have, from the Kew tables, 
«=6'-365 corresponds to l+jj- = 1-00118. 
Clock Rate. 
The Kew observations are corrected for clock rate. 
Owing to an accident to the comparing chronometer, the rate of the Pixholme clock was 
not determined till two or three days after the conclusion of the vibration experiments. 
