FORMA TION OF ME TEORFFES 383 



gaseous body A upon the Roche sphere of the body B, self- 

 gravitation, in accordance with Roche's doctrine, will have been 

 completely neutralized on the lines joining the centers of A 

 and B, and its restraining influence upon the elasticity of the 

 gaseous body on these lines will have been removed, while the 

 gravitative constraint in the transverse section will be increased. 

 The expansive energy of the compressed gaseous matter will 

 therefore be left to exert its full projectile force m the direction 

 of the axis of elongation. While I am unable to offer a numeri- 

 cal estimate of the magnitude of this expansional energy in such 

 a body as the sun, it is certainly of a high order of magnitude. 

 The speed at which prominences are projected from the sun 

 under present conditions closely approximates to the parabolic 

 velocity with respect to the sun, and this is accomplished in 

 spite of gravitation and a resisting atmosphere. 



The case in hand, therefore, starts with simple tidal elonga- 

 tion at a distance, and increases to an explosive maximum as the 

 bodies approach periastron. This increase is at first gradual, but 

 in the last stages of approach to periastron the acceleration is 

 exceedingly rapid. In any attempt to follow the process in 

 more detail, adhering to the recognized principles of tidal action, 

 four particulars are of special moment : (i) the progressive elon- 

 gation of the body, (2) the change in the direction of tidal dis- 

 tortion, (3) the lag of the line of maximum elongation behind 

 the line of maximum attraction, and (4) the rotatory effects 

 arising from the gravitation of B on the tidal protuberances of A, 

 which in this case will be peculiarly effective because of the 

 enormous distortion of A and the very close proximity of B at 

 the critical stages. The principles from which these effects arise 

 are thoroughly demonstrated and are familiar to all students of 

 tidal phenomena, and it is only their special applications to this 

 case that need be discussed. The rotatory effects are a little 

 peculiar in that both of the tidally acting bodies are rapidl}- 

 approaching each other, and developing extraordinarily powerful 

 differential attractions, while at the same time they are swinging 

 about their common center of gravity. Near periastron they 



