Aidan
master brummie
You have to give it to Thomas Edison - he was prolific - if not always on the right lines, perhaps the time has not yet come for the Aerophone (though some people's use of the modern Mobile, one could be forgiven for thinking so - "I'M ON THE TRAIN" etc).
The Aerophone consisted of a speaking trumpet controlled by the outflow of compressed air which amplified the human voice. It could be heard clearly through receiving hearing trumpets as far as six miles. Read more in The NY Times 25 Mar 1878 https://query.nytimes.com/mem/archive-free/pdf?_r=1&res=9E0CE7DA163FE036A05756C2A9659C946990D7CF
In "Edison, His Life and Inventions" it is described as "a steam machine which carried the voice a distance of one and a half miles."
The Aerophone consisted of a speaking trumpet controlled by the outflow of compressed air which amplified the human voice. It could be heard clearly through receiving hearing trumpets as far as six miles. Read more in The NY Times 25 Mar 1878 https://query.nytimes.com/mem/archive-free/pdf?_r=1&res=9E0CE7DA163FE036A05756C2A9659C946990D7CF
In "Edison, His Life and Inventions" it is described as "a steam machine which carried the voice a distance of one and a half miles."