Lf. H. Bigelow—The Earth a Magnetic Shell. 97 
meteorology has heretofore considered only the effect of the 
electro-magnetic radiation. It seems clear that the general 
theory of cyclones must be somewhat recast, especially because 
the existing treatment has introduced so many limiting condi- 
tions as to deprive the result of the possibility of any strict 
comparison with the phenomena of nature. The three most 
pressing problems in our study are now: 
(1.) The transformation of radiant energy into heat. 
(2.) The distribution of magnetic activity in the nucleus of 
the sun. 
(3.) The true stream line circulation in the anticyclones and 
the cyclones. 
In all of them some progress has already been made. On 
comparing the values of s, o, for the field south and north 
respectively, it is seen that the vectors pointing from north 
of the ecliptic towards the south, always exceed those oppo- 
sitely directed, by several units in the 5th decimal place. It 
indicates some persistent physical difference, and it may be that 
the north pole of the sun is stronger and positive as compared 
with the southern. For this and the phenomenon that has 
been called “inversion of temperatures,” no _ satisfactory 
explanations have been discovered. | 
Since these vectors represent cosmical forces of the same 
‘mechanical type as gravitation, connecting the sun with the 
planets, it would seem that they should be taken into account 
in general theoretical astronomy, or the celestial mechanics of 
the solar system. 
We have been accustomed to think of gravitation as the 
only mechanical force between the sun and the planets, and 
theoretical astronomy has been constructed upon this basis. 
Yet there are several outstanding secular motions that appar- 
ently fail to comform to the simple Newtonian Law of the 
inverse square of the distance. Thus Newcomb gives in “ Astro- 
nomical Constants,” 1895, (1) the motion of the perihelion of 
Mercury, (2) the motion of the node of Venus, (8) the motion of 
the perihelion of Mars, (4) the eccentricity of Mercury, as the 
most important divergences of theory and observation. To 
account for these motions the following hypotheses of the 
action of unknown masses of matter are discussed : 
1. The non-sphericity of the Sun. 
2. An intra-Mercurial ring or group of planetoids. 
3. An extended mass of diffused matter like that which reflects 
the zodiacal light. 
4, Aring of planetoids between the orbits of Mercury and 
Venus. 
Am. Jour. Sct.—TuirD SERIES, Vou. L, No. 296.—Avueust, 1895. 
7 
