﻿connected with Astronomical Physics. 573 



remains the reconciliation of apparent disagreements will 

 have become obvious." {' Nature,' August 31, 1905, p. 439.) 



" To conduct the attack in various ways at the same time," 

 being tantamount to ' keeping of all alternative possibilities in 

 view," may accordingly be a motive for inviting attention to 

 some other aspects of the inquiry; while some extracts from 

 Sir Greorge Darwin's address appear to lend additional 

 support to the view that planets may be formed by the 

 accretion of meteoritic matter. First, by way of preface, 

 he says : — 



"The German astronomer Bode long ago propounded a 

 simple empirical law concerning the distances at which the 

 several planets move about the sun. It is true that the 

 planet Neptune, discovered subsequently, was found to be 

 considerably out of the place which would be assigned to it 

 by Bode's law, yet his formula embraces so large a number 

 of cases with accuracy that we are compelled to believe that 

 it arises in some manner from the primitive conditions of the 

 planetary system. 



" The explanation of the causes which have led to this 

 simple law as to the planetary distances presents an interest- 

 ing problem, and, although it is still unsolved, we may obtain 

 some insight, into its meaning by considering what I have 

 called a working model of ideal simplicity. 



" Imagine then a sun round which there moves in a circle 

 a single large planet. I will call this planet Jove, because it 

 maybe taken as a representative of our largest planet, Jupiter " 

 (' Nature/ August 31, 1905, p. 439). 



Next, a number of meteorites (some of which may be 

 even comparable in size to asteroids) are supposed to be 

 moving in all conceivable directions, so that certain of them 

 fortuitously may enter the system composed of the sun and 

 Jove. By mathematical analysis, it is found that there are 

 certain " zones surrounding the sun and Jove in which stable 

 orbits are possible, and others in which they are impossible. 

 There is hardly room for doubt [it is added] that if a com- 

 plete solution for our solar system were attainable, we should 

 rind that the orbits of the existing planets and satellites are 

 numbered amongst the stable perpetual orbits, and should 

 thus obtain a rigorous mechanical explanation of Bode's law 

 concerning the planetary distances" (p. 439). 



Previously it is remarked that while some of these meteo- 

 ritic bodies " will be absorbed by the sun," a " minority will 

 collide with Jove." 



The process by which the meteorites, — which (it seems) 

 must gradually accumulate more and more within the limits 



