By Robert Steel Edgar (auth.)
"Electromagnetic thought is a unusual topic. The peculiarity is living no longer loads within the stratification - superposed layers of electrostatics. magnetostatics. regular currents and time-varying fields - as within the failure that has attended all makes an attempt to weld those layers right into a logical entire. the bottom layer. electrostatics. defines yes strategies. akin to E. D, ~, in a manner that's commonly passable just for the static case. but the try is made to strength those specialized definitions into the better strata, with advert hoc alterations while worthy. the coed, in searching through his textual content books on electromagnetics, can locate normal definitions in simple terms with trouble. if in any respect; or even the main complex treatises fail to provide a carefully logical improvement of the subject". 1 So wrote Moon and Spencer a few 30 years in the past; and their feedback is still pertinent at the present time. 2 extra lately. a senior physicist of the nationwide Bureau of criteria has expressed his hindrance in comparable phrases: "A logically constant set of definitions of the electromagnetic box amounts is intensely tricky to discover within the literature. so much textual content books both sidestep the matter or current definitions which are appropriate in basic terms to big cases".