224 
BIGELOW. 
Professor Newcomb has recently done by the same least- 
square process. Now, in the case of the resulting 26.68-day 
rotation period there is a further complexity to be considered. 
The intensity curve is not simple, but it is one having several 
crests about three days apart, and this shows that the solar 
output is very unsteady in longitude as well as in latitude. 
If this curve is developed quite loosely in longitude and the 
crests move back and forth, as is natural in that congested 
struggling medium, then there is a tendency for the crests 
of the curve in one period to fall upon the corresponding 
hollows in another period, and thus the maxima and the 
minima neutralize each other. The result of this fluctuating 
action is that there is an excessive waste in the summation 
of the numerical matter, whether by the graphic or the 
periodogram methods, and the inference that no average 
period exists is a misapplication of the logical conclusions 
that should be made. If, then, a fixed period is adopted? 
and the least-square theorems are rigidly applied as if the 
events were simply independent and recurring at random, a 
a negative result will certainly be obtained. Hence, it is 
evident that one should be very cautious in the application 
of mathematical analysis to the observations of solar physics 
generally, and negative results will have very little critical 
value unless this has been done. It may be well to point 
out in this connection that the 11-year period of solar-spot 
formation is confined to the middle latitudes of the sun, from 
+ 50° to — 50°, and that both polar regions are quite free 
from this special periodic phenomenon. This result was ob¬ 
tained from the discussion of the Italian observations on the 
solar prominences, which in the middle zones have the same 
11-year period as the spots and the faculaB, but do not con¬ 
tinue with this period into the polar latitudes. That fact 
suggests that too much emphasis may have been laid upon 
the 11-year synchronism in discussing these solar-terrestrial 
problems. On the other hand, have found a 3-year cyclic 
recurrence which is more characteristic of the entire surfaec 
of the sun, and this short cycle has been shown to exist 
