Did you know the rubber hot water bottle was a Croatian invention? Eduard Slavoljub Penkala was a madly productive inventor, better known for his work in developing a kind of mechanical pencil (patented in 1906). While he was at it, he developed a fountain pen with solid ink, the thermos flask, a rotating toothbrush, various railway-related innovations, and built a biplane. Presumably his invention of the hard rubber from which gramophone records were once made was related to his invention of the hot water bottle and thermos flask.
I can't tell you quite how true all these claims are. I suspect most of them are mostly right, but the history of invention is usually more complicated than it looks on the surface, and these claims for Penkala's accomplishments all come from either Wikipedia or websites devoted to praise of the inventor. Versions of mechanical pencils, for example, were in development from at least 1822. As for the hot water bottle, if superficial web searches have any more to tell me about its origins, I haven't found them. But then again, I wasn't looking too hard. After all - I am nominally sick. Well. One of my ears is anyways.