548 THE POPULAR SCIENCE MONTHLY 



slowly (through chemical attraction), then more rapidly (through the 

 so-called Newtonian attraction), and always in proportion as its mass 

 increases, draws the surrounding parts more and more strongly to unite 

 with itself." This central body is not strictly to be called a sun at the 

 outset, for it is not yet " in a flaming state " ; this it only gradually 

 becomes as, in the course of the subsequent processes of readjustment, 

 " the lighter and more volatile portions of the primitive matter," fail- 

 ing to maintain a movement of periodic revolution, drop into the center 

 of attraction. (2) The formation of a whirl of unaggregated particles 

 moving round this central body in circular but separate and intersect- 

 ing orbits. 



When the mass of the central body has grown to such a point that the 

 velocity with which it draws particles to itself from great distances is, by the 

 weak degrees of repulsion with which the particles impede one another, deflected 

 into lateral motions which, by virtue of centrifugal force, encompass the central 

 body in an orbit — then there are produced great whirls of particles, each of 

 which, by reason of the composition of the gravitational force and the force 

 making for deflection sideways, describes a curved line. These orbits all inter- 

 sect one another . . . and are in conflict with one another. 



(3) The transformation of this disordered whirl of particles into a 

 ring or disc of particles moving in free, parallel, circular orbits round 

 the central body. The conflicting movements of the preceding stage 

 come eventually to such an adjustment that they interfere with one 

 another as little as possible. This happens in two ways : 



First, by the particles limiting each others' movements till they all advance 

 in one direction; second, by their limiting their vertical movements towards the 

 center of attraction till, all moving horizontally in parallel circles round the 

 sun as their center, they no longer intersect one another's paths, and, by the 

 equalization of the centrifugal and centripetal forces, they maintain themselves 

 constantly in free circular orbits. In this state, when all the particles are 

 moving in one direction and in parallel circles, the conflict and collision of the 

 elementary bodies is annulled, and all things are then in the condition of least 

 reciprocal interference. 



Further, " in acordance with the laws of centrifugal motion, all 

 these revolutions must intersect the center of attraction with the plane 

 of their orbits " ; and for bodies moving in a common direction round a 

 common axis, there is only one such plane. Therefore, the revolving 

 particles gather about " that circle which passes through the rotation 

 of the axis in the center of the common attraction," and the system 

 assumes (though there are as yet no planets) that discoid form char- 

 acteristic of our present planetary system. (4) The gradual formation, 

 within this ring, of planets, through the attractions subsisting between 

 the separate particles composing it. Kant has hitherto treated attrac- 

 tion chiefly as operative between the central mass and the particles; 

 between particle and particle the relation has been one of repulsion. 

 But at this point, " the attraction of the elementary bodies for one 

 another begins to produce its effect, and thereby gives the start to new 



