  Slowly rotating collapsing spherical shells have flat spaces inside and the
inertial frames there rotate at omega_s(t) relative to infinity. As first shown
by Lindblom & Brill the inertial axes within the shell rotate rigidly without
time delays from one point to another. Although the rotation rate of the
inertial axes is changing the axes are inertial so, relative to them, there is
neither an omega dot_s times r (Euler) fictitious force nor any other. However,
Euler and other fictitious forces arise in the frame which is at rest with
respect to infinity. An observer at the center who looks in one direction (phi
= 0, theta = pi/2 say) fixed to infinity will see that the sky appears to
rotate and can compare its apparent rotation with those of the local inertial
frame and of the shell itself. By contrast in the electromagnetic analogue
there is a time delay in the propagation of the magnetic field inside a
rotating collapsing charged shell in flat space. We demonstrate this time delay
by devising a null experiment in which the Larmor precession of a charged
oscillator would be exactly cancelled by the rotation of the inertial frame but
for the delay. In the ``combined'' problem of a collapsing charged shell we
show that, due to the coupling of electromagnetic and gravitational
perturbations, the instantaneous rotation of inertial frames inside the shell
can be caused by pure electric currents in a non-rotating shell.
