134 Prof. A. M c Aulay on Sj^ontaneous Generation 



for a closed curve, and \\d%' = for a closed surface. We 

 obtain 



lyv^y^O, (18) 



(mT'-OiVi^O. . . . : . (19) 



(18), which may also be written 



Xl YcVi = (20) 



is deducible directly from the definition of T or of %. 

 (19) is deducible directly from the following known fact: — 



Th. 9. mT / - 1 Q>=-iVp 1 / p 2 'Sa)ViV2 ) • • • (21) 



^S'=-iVp/ / a 2 'S^ViV2. • • • (22) 



Th. 10. am=mT / - 1 (23) 



Th. 11. If any one of the four scalars m, m', m", m"', 

 occurs as a term in w it produces no effect whatever on the 

 bodily equation of motion. 



Some ten or twenty other " known " theorems, similar in 

 their fundamental nature and importance to the above eleven, 

 could be enunciated, but they are not required below\ Would 

 it require one hand or two bands to furnish fingers sufficient 

 to count the physicists of the world who know them ? 



III. Description of first JEtlier Hyjiothesis. 



Some steps are taken below in the direction of rendering in- 

 telligible the fundamental assumptions of Sir Joseph Larmor's 

 system of the universe as explained in his ' iEther and 

 Matter.' He finds, largely from the researches of MacCullaoh 

 and Maxwell, that those natural records which we have most 

 successfully read well-nigh compel us to assert that the jether 

 behaves as if it were a " rotationally elastic " medium. In 

 an admirable manner, the consequences of postulating this 

 much and as little as possible more, are developed in the 

 treatise. The development, which seems to have been Sir 

 Joseph Larmor's chief object, and which certainly occupies 

 the greater part of the treatise, does not concern us here so 

 much as the foundation. 



Occasionally Sir J. Larmor seems, in a half apologetic 

 manner, to invite us to regard the " rotationally elastic " 

 property as something of an ultimate nature, behind w r hich 

 there should be no urgent demand to go. Whether or not 

 this invitation is really intended, most of us cannot tolerate 

 the mental attitude here alluded to with comfort. We have 

 the same instinctive objection to an elastic resistance to 

 absolute rotation of a medium, as w r e have to action between 

 bodies at a distance ; both alike we seek to " explain " by 





