WHAT IS ELECTRICITY? HEYL 233 



a slow death of positive electricity due to the centripetal acceleration 

 produced by the earth's rotation. 



To account for the known electrical facts, there is necessary an 

 annihilation of less than one proton per cc per day, equivalent to a 

 loss of 0.5 percent of the earth's mass in 10-° years. This would 

 also account for as much of the earth's magnetic field as is sym- 

 metrical about the earth's axis, and would give the correct ratio for 

 the magnetic fields of the earth and the sun. Moreover, no develop- 

 ment of charge or magnetic field could be detected with a sphere 

 of laboratory size rotating at the highest practicable speed. And 

 finally, Swann's scheme is consistent wdth the special theory of 

 relativity. 



Whatever may be thought of Swann's fundamental assumption, 

 it must be admitted that his theory is experiment-proof. Moreover, 

 even though it should be definitely disproved, it would have the last- 

 ing merit of impressing upon us caution in extrapolating laboratory 

 results to the cosmic scale. 



The relations of newly discovered fact and existing theory are, as 

 we have seen in this somewhat brief survey, rich in suggestion. 

 Speculation is not dead but sleeping. If the past is still an indica- 

 tion of the future, it will awake again to renewed activity, and when 

 this occurs we will need a wide acquaintance with fact and a good 

 sense of perspective to guide and direct future sj^eculation on the 

 question : What is electricity ? 



