1245 
the case to a much less degree. Paths of particles which have high 
radial velocities and therefore exhibiting extraordinary inclinations 
are shooting again and again through the field of view of the telescope. 
In the experiments of § 6 and $ 7 the accuracy of the adjustment is not 
so much lowered by this phenomenon, though even here such 
deviating paths are visible from time to time. Summarising the 
results of § 6 and $ 7 by taking the mean of the values of y we 
obtain 0,843. *) 
If we assume that over a length of 10 em. a smaller value of 
y holds, this has no perceptible influence on the final result, as in 
Fizrav’s experiment the whole length of the tube is 300 em. For an 
estimate of the accuracy of the determinations I give here as an 
example those referring to the last observation of § 7. 
V= 762 L T= 696 seconds. 
Reading of the divided circle. 
Direction of rotation of the mirror: 
to the right to the left 
308.2 218.1 
307.0 2155 
310.5 218.2 
309.9 218.0 
309.1 215.4 
308.2 219.5 
309.8 218.8 
307.0 218.9 
307.8 219.0 
311,3 219.6 
308.8 218.3 
Difference = 2a = 90°5, «a = 45°,3. 
It is difficult to estimate the accuracy of the determination g —0,845, 
but we shall not be far from the truth, if we call a deviation of 
more than 1°/, very improbable. An effort to increase the accuracy 
by an accumulation of observations would only then have sense if 
we were quite sure that the influence of the strongly deviating paths 
on the optical phenomena might be neglected, which is very probable, 
and if the measurements could be made with the same tube that 
was used in Fizrav’s experiment. This is not well possible. It is 
however not necessary to justify an important conclusion concerning 
1) The mean of all observations of § 6—§ 8 gives 0.839. 
