Nothing there.I'm not sure. Try reading the papers linked in this article.
https://en.wikipedia.org/wiki/Oliver_Heaviside
OK. The original derivation of radiation speed is too difficult for me. I don't really know how our modern EM speed derivation may be related or compared to Maxwell's original.Maxwell didn't actually use the equation ##v = \frac 1 {\sqrt {\mu_0 \epsilon_0}}##. That equation uses SI units which hadn't been codified in Maxwell's day. He used a different set of units, and indeed different names for many electromagnetic quantities. The equation we use nowadays should be considered a modern "translation" or "interpretation" of Maxwell's calculations. For what it's worth, you can see what Maxwell actually wrote when he calculated the theoretical speed of his electromagnetic waves:
https://en.wikisource.org/wiki/Page:Philosophical_magazine_23_series_4.djvu/38
In the cgs system in use at that time (and also when I was at school) there are two sets of units, emu and esu. The emu is current (charge x velocity) necessary to produce a force of 1 dyne between two conductors, and the esu is the charge necessary to produce a force of 1 dyne between two charges, all spaced 1cm. For a vacuum, permeability and permittivity were defined as 1. Maxwell noticed that the ratio of these two units was about equal to 3 x 10^8 m/s, which is c.OK. The original derivation of radiation speed is too difficult for me. I don't really know how our modern EM speed derivation may be related or compared to Maxwell's original.
Great! Very helpful. Though I don't understand it now, this is the hint if I want to investigate further. I do know that the force between currents in conductors is related to the magnetic field and thus to permeability. The other is simply related to permittivity.In the cgs system in use at that time (and also when I was at school) there are two sets of units, emu and esu. The emu is current (charge x velocity) necessary to produce a force of 1 dyne between two conductors, and the esu is the charge necessary to produce a force of 1 dyne between two charges, all spaced 1cm. For a vacuum, permeability and permittivity were defined as 1. Maxwell noticed that the ratio of these two units was about equal to 3 x 10^8 m/s, which is c.