344 



Sir Joseph LanTwr, Gravitation and Light 



spectral periods were definitely disproved, then it would appear 

 that any hope of bringing orbits into direct relation with the 

 electrodynamic space-time fourfold must be abandoned altogether*, 

 on the threshold. This drastic conclusion is perhaps an argument in 

 fa^^our of the existence of the effect. 



The other two verifiable effects, the influence on the planetary 

 perihelia and the deviation of light passing near the Sun, arise in 

 part from first order and in part from second order causes. Unlike 

 the previous one, their exact verification is thus a test of the special 

 theory of Einstein, or the equivalent Least Action formulation. Its 

 original recommendation was that it restricts the universal forces 

 of nature to the one type of gravitation: possibly it would be 

 difficult to imagine ways in which there could be room for any 

 different result. 



* A formulation of the original Nordstiom type, starling from d^Vda = 0, is to 

 some degree an exception. 



