Good catch - "blower". I still use that term myself and so do several others in my acquaintance. Even kids understand what I mean so it is definitely embedded in the national conscience here still or at least they get the idea by reference and context.

Without any research whatsoever I'll also venture that "blowing" is what people used to do when they had to rush downstairs to answer the new fangled telephonic device and ended up out of breath. However, again without research, there is a good chance that the RN and co would have referred to the voice tubes on ships as "blowers" because that is the sort of word they would pick. I know a lot of modern matelots and that theory fits nicely.