60 ROCHESTER ACADEMY OF SCIENCE. [May 26, 
manifest on the very days when they appear at the eastern limb by 
rotation. Applying the methods suggested in that discussion, and 
judging as to the activity of solar disturbances by their history at 
successive returns, and by their relation to magnetic and likewise to 
electrical phenomena, which are reciprocal, as well as by their appear- 
ance, it becomes possible to note critical dates and institute an inquiry 
as to whether such disturbances bear any immediate and positive 
relation to changes in the distribution of atmospheric pressure. 
Following this method, it appears from the International Weather 
Maps that barometric depressions are, as a rule, at once deepened at 
all points from which observations are to be had, when active solar 
disturbances are appearing by rotation at the eastern limb. Anti- 
cyclones also tend to move eastward at such times. In other 
words an impulse of some sort seems to be imparted to the entire 
atmosphere, isobars becoming more crowded, winds stronger, and all 
meteorological phenomena more intense, changes in the distribution of 
pressure becoming manifest in due course. At times when such 
impulses are given in rapid succession their effect does not appear in 
such strongly contrasted conditions from day to day as when a single 
energetic outbreak follows a period of comparative calm, as was the 
case in last March. 
From evidence such as that adduced we are justified in assuming, 
as a working hypothesis at least, that the distribution of atmospheric 
pressure as a whole may be determined to an important extent by the 
fact that the earth is a magnet, and that its magnetic properties are 
variable. Certainly the distribution of the solar atmosphere bears a 
direct relation to the sun’s magnetic condition, the changes in its visible 
condition being associated directly with variations of magnetic range 
and prevalence of auroras. 
It is not proposed to discuss the details of this hypothesis, but to 
outline some of its leading features. As an illustration of the manner in 
which it may be worked out in detail it may be proper however to refer 
to a single point. This hypothesis makes possible a new explanation 
of the persistence of high pressure over parts of the earth in which 
winter prevails. It is well known that heat decreases magnetic power, 
and it is perfectly consistent, other things being equal, that the atmos- 
phere, if controlled by magnetic forces, should attach itself in greater 
measure to the colder parts of the earth. Thus the belt-like arrange- 
ment may be due to the earth’s total force as a magnet, and the modi- 
fications of this distribution at different seasons may be related to local 
temperature conditions. Certainly such persistent heaping up of the 
