  The duality between the original Kaluza's theory and Klein's subsequent
modification is duality between slicing and threading decomposition of the
five-dimensional spacetime. The field equations of the original Kaluza's theory
lead to the interpretation of the four-dimensional Lorentzian Kerr and
Taub--NUT solutions as resulting from static electric and magnetic charges and
dipoles in the presence of ghost matter and constant dilaton, which models
Newton's constant.
