Oliver Heaviside

• SORRY to be boring and it’s nice to have a blue plaque in Camden Town for Oliver Heaviside, who theorised about the “Heaviside layer”, an invisible mirror for radio waves a hundred miles high in the sky, (A plaque for maths genius Oliver Heaviside, April 28).

Heaviside is how radio stations are some­times heard in far-off lands. The signals bounce and skip across the world. But this wasn’t the “key for mobile phones”. Cellphones make calls world-wide by sending signals over many short distances.

It may sound pernickety to point this out, but with so many people (who happily talk non-stop on today’s mobile phones) hell-bent on objecting to 5G cellphones, which work on similar frequencies over similar short distances to today’s phones, it’s best not to provide any more misinformation for misquoting.

BARRY FOX, NW3