The Astronomical Outlook 



attribute them to errors of observation, inaccu- 

 racy of the computer, or real error in the funda- 

 mental statement of the ' ' law. ' ' 



Thus far we have no satisfactory physical ex- 

 planation of the mysterious force which produces 

 the so-called "attraction" between masses of 

 matter, however remote from each other, nor 

 does any valid reason appear why it should vary 

 "inversely as the square of the distance" be- 

 tween them. It is simply a fact of observation 

 that such a force exists, and that it follows the 

 law assigned with remarkable if not absolute 

 precision. It remains for the future to show 

 just how it is related to the other forces of nature, 

 to attractions and repulsions which we designate 

 as chemical, electric, and magnetic, and to the 

 energies transmitted by the various forms of 

 radiation. It is almost certain that these are 

 all consequences of the constitution of the so- 

 called "ether" the hypothetical substance that 

 fills all space, indispensable to the physicist, and 

 yet almost inconceivable in the nearly self-con- 

 tradictory properties which have to be assigned 

 to it in order to account for its behaviour and 

 functions. We do not mean to intimate- that 

 astronomy alone will ever be able to solve the 

 difficult problems which are suggested in this 

 connection, but only that the motions of the 

 planets and the stars will throw light upon them, 

 and will themselves find elucidation as the results 

 of physical research gradually clear up the 

 origin and theory of the "pulls and pushes" 



