"Veins bulging purply from their foreheads" meaning

Question

I was reading Historical Linguistics by Larry Trask Revised by Robert McColl (Chapter I, The fact of language change - Topic: Attitudes to language change) and came across an unfamiliar phrase:

Veins bulging purply from their foreheads

I've never heard it and searching it on Google didn't help.

Here's the paragraph:

This curious (to us) construction was the only possibility in the eighteenth century, and when a few innovating speakers began to say things like My house is being painted, the linguistic conservatives of the day could not contain their fury. Veins bulging purply from their foreheads, they attacked the new construction as ‘clumsy’, ‘illogical’, ‘confusing’ and ‘monstrous’. But their efforts were in vain. Today all those who objected to the ‘illogical’ and ‘monstrous’ new form are long dead and the traditional form they defended with such passion is dead with them.

Trask was talking about old grammatical constructions that are no longer in use. But the emboldened phrase wasn't one of those constructions. Does anyone know what it means?

Answer 1

Veins bulging or appearing prominently on someone's head is a sign that they're strained or angry.

The author is using this phrase (and what a funny and weird adverb, "purply") to imply how angry and upset the linguistic pundits of the time were at these new constructions like "My house is being painted". They were so upset that you could imagine purple veins popping out on their heads.