and further

(48) |
$\Phi _{4}={\frac {i[{\mathfrak {wE}}]}{\sqrt {1-{\mathfrak {w}}^{2}}}}$, |

Because *F* is an alternating matrix,

(49) |
$w{\overline {\Phi }}=w_{1}\Phi _{1}+w_{2}\Phi _{2}+w_{3}\Phi _{3}+w_{4}\Phi _{4}=0$, |

*i.e.* $\Phi$ is perpendicular to the vector to *w*; we can also write

(50) |
$\Phi _{4}=i({\mathfrak {w}}_{x}\Phi _{1}+{\mathfrak {w}}_{y}\Phi _{2}+{\mathfrak {w}}_{z}\Phi _{3})$, |

I shall call the space-time vector $\Phi$ of the first kind as the *Electric Rest Force*.

Relations analogous to those holding between $-wF,\ {\mathfrak {E,\ M,\ w}}$, hold amongst $-wf,\ {\mathfrak {e,\ m,\ w}}$, and in particular *-wf* is normal to *w*. The relation (C) can be written as

{C} |
$wf=\epsilon wF$ |

The expression (*wf*) gives four components, but the fourth can be derived from the first three.

Let us now form the time-space vector 1st kind $\Psi =iwf^{*}$, whose components are

${\begin{array}{cccccccccc}\Psi _{1}&=&-i(&&&w_{2}f_{34}&+&w_{3}f_{42}&+&w_{4}f_{23}),\\\Psi _{2}&=&-i(&w_{1}f_{43}&&&+&w_{3}f_{14}&+&w_{4}f_{31}),\\\Psi _{3}&=&-i(&w_{1}f_{24}&+&w_{2}f_{41}&&&+&w_{4}f_{12}),\\\Psi _{4}&=&-i(&w_{1}f_{32}&+&w_{2}f_{13}&+&w_{3}f_{21}&&).\end{array}}$
Of these, the first three $\Psi _{1},\ \Psi _{2},\ \Psi _{3}$ are the *x-, y-, z-*components of the space-vector

(51) |
${\frac {{\mathfrak {m}}-[{\mathfrak {we}}]}{\sqrt {1-{\mathfrak {w}}^{2}}}}$, |

and further

(52) |
$\Psi _{4}={\frac {i[{\mathfrak {wm}}]}{\sqrt {1-{\mathfrak {w}}^{2}}}}$; |

Among these there is the relation

(53) |
$w{\overline {\Psi }}=w_{1}\Psi _{1}+w_{2}\Psi _{2}+w_{3}\Psi _{3}+w_{4}\Psi _{4}=0$, |

which can also be written as