68 PROFESSOR C. V. BOYS ON THE 

Ang. 21. | Aug. 23. | Aug. 25. | Aug. 26. | Aug. 27. | Aug. 29. 

3669:0 | 3667-7 36658 3669°7 3668°3 36683 
3669°6 3668 (36649) 3669:0 
a: 3666°7 3665°7 aS ore 3669°4 
3667°8 
Temperature at 1! 40.43 @. | 179-04 C.| 16°58 C. | 16°56 C. | 16°59 C. | 18°24 0. 
end of night 









The mean of all but the one in brackets, which depends on a single value only, is 
36681. The deflection for Experiment 5 is 3668°6, practically an identical quantity, 
so that the G and A of the two are almost the same. The two results should properly 
be considered as one. Both unfortunately depend upon unsatisfactory period obser- 
vations which, when squared, varied from 37200 to 37240. On this account the 
results from Experiments 4 and 5, which are higher than any of the others for G and 
lower for A, should have had a bad mark put against them. In Experiment 6 the 
deflections were nearly as consistent as those in Experiment 4, while the periods were 
now nearly the same in the + and — positions, being, when squared, 37245 in the — 
and 37247 in the + positions, The conditions of this experiment seemed decidedly 
favourable, and I see no reason inherent in the observations that could lead me to 
doubt the accuracy of the results. 
In Experiment 7 the only change was twisting the lead balls so that the sides that 
were inwards should be outwards. The sudden change in the result for A from 
5°5189 to 5°5291 might seem to be due to some irregularity of density in the lead 
balls. But the extraordinary agreement between this result and the three following, 
where every kind of change was made in the conditions, including the turning of the 
balls again, and the change from high to low and low to high, and where, moreover, 
the extra steadiness of temperature due to the screening of the octagon house was 
introduced, shows that this argument will not hold. I cannot account for this small 
difference. In Experiment 8 all the conditions were most perfect. The figures for 
this have already been given, and so need not be repeated. I may, however, compare 
the squares of the periods of Experiments 6, 7, and 8, throughout which the beam 
mirror and gold balls were never touched, to show how much better the agreement 
was at this time than before. 



| Experiment. Date. — position. + position. 
|_ 
6 Sept. 14. 37245 37247°5 
7 m do 37242 
8 pee ae 37245'9 




The last figure of this series was taken in determining 8. I may mention that a 

