, two of which are very low and one rather high. But a glance at all the other data which I have published on oil drops shows the complete falsity of this position,[119] for these data show that after I had eliminated dust all of my particles yielded exactly the same value of “
” whatever their size[120]. The only possible interpretation then which could be put on these two particles which yielded correct values of
, but too slow rates of fall, was that which I put upon them, namely, that they were not spheres of oil.
As to the Vienna data on mercury and gold, Dr. Ehrenhaft publishes, all told, data on just sixteen particles and takes for his Brownian-movement calculations on the average fifteen times of fall and fifteen of rise on each, the smallest number being 6 and the largest 27. He then computes his statistical average
from observations of this sort. Next he assumes Perrin’s value of
, namely,