2o6 CARNEGIK INSTITUTION OF WASHIxNGTON. 



If the question be pushed a step farther, to inquire how small 

 bodies hke the asteroids may be rendered specially subject to the 

 requisite conjunctions, th^ answer may be found in the approach of 

 suns to one another, attended by such secondaries. For example, 

 if the solar system were to pass even within five or six billion miles 

 of a similar system, the orbits of the secondaries would be very 

 greatly perturbed and an intricate and prolonged series of changes 

 would ensue. These are too complicated to be followed by compu- 

 tation, but there are grounds for believing that they might involve, 

 sooner or later, through their disturbed courses, the close approach of 

 some of the smaller bodies to some of the larger. These smaller 

 bodies in the solar system are numbered by hundreds, and similar 

 numbers may be suspected to belong to other systems, and this 

 largeness of number adds to the probabilities of .some close approaches 

 during a condition of general disturbance. 



The solar system is probably not the most favorable selection for 

 illustrating the contingencies of such disturbance, for it is a simple 

 isolated system, with a single overpowering center that convoys 

 its attendants by a scarcely disputed control. From its symmetry, 

 it is to be inferred that it has swept through space undisturbed 

 throughout the period of its existing organization. But there are 

 many binary, triple, multiple, and clustered systems of suns which 

 apparentl}' divide the control of a common field, and this divided 

 control may reasonabl}- be supposed to involve approaches of the 

 chief bodies of sufficient nearness to one another to perturb seriously 

 their outlying secondaries and introduce disturbances ultimately in- 

 volving disruptive approaches. The nebulous matter associated with 

 some of these perhaps implies something of this kind. 



The hypothesis of disruption by differential attraction may be 

 pushed one step farther by postulating that the disrupted group of 

 fragments may in its earlier history constitute a comet, since it is the 

 general behef of astronomers that the comet's head is composed of a 

 cluster of small bodies. The peculiar emanations which arise from 

 a comet may perhaps as plausibly be referred to the occluded vapors 

 and the radio-active substances of a shattered asteroid as to any other 

 recognizable source. The recent discoveries of the prevalence of 

 radio-activity and allied phenomena render the cometic emanations 

 less strange and exceptional than they once seemed. 



The fragments of an asteroid or other small body disrupted in 

 this manner would, it is believed, be given a rotatory movement by 

 the differential attraction that produced them, and hence the result- 



