  Pulsars are rapidly spinning highly magnetised neutron stars. Their spin
period is observed to decrease with time. An early analytical model for this
process was the vacuum retarded dipole (VRD) by Deutsch in his 1955 paper "The
Electromagnetic Field of an Idealized Star in Rigid Rotation in Vacuo" (D55).
This model assumes an idealised star and it finds that the energy is radiated
away by the electromagnetic fields. This model has been superseded by more
realistic numerical simulations that account for the non-vacuum like
surroundings of the neutron star. However, the VRD still provides a reasonable
approximation and is a useful limiting case that can provide some qualitative
understanding. We provide a detailed derivation of the spin down and related
field equations of the VRD. We also correct a typo found in the general field
equations in D55.
