What did Bell invent?

American scientist Bell invented the telephone and hearing aid.

Bell invented the first available telephone in the world and founded Bell Telephone Company. He was praised as the "father of the telephone" by the world, and also made hearing AIDS and improved the phonograph invented by Edison. Not only that, Bell also made great contributions to the invention of deaf-mute language. Therefore, Bell is not only an inventor, but also an entrepreneur.

Bell also improved the phonograph invented by Edison, who made great contributions to the invention of deaf-mute language. He wrote 100 articles and pamphlets. 188 1 year, in order to find the bullet in American President james garfield, he designed a metal inspection device, which is the predecessor of the X-ray machine. He also founded the British Association for the Promotion of Deaf Education and invented hearing AIDS.

Bell's life:

1847 On March 3rd, Alexander Graham Bell was born in Edinburgh, Scotland, where he received primary education. Bell 1870 immigrated to Canada and arrived in the United States one year later. He became an American citizen on 1882. Bell himself is an acoustic physiologist and a deaf-mute language teacher. Before him, the German Philip Rice had invented the telephone, but its sound transmission effect was too poor to be used in practice. On March 1876, Bell and his colleagues tested the world's first available telephone.

1895 graduated from Paris Teachers College, and became a math teacher in public Nancy Middle School in the same year. Four years later, he received a doctor's degree from a higher normal school. His doctoral thesis, The Theory of Real Variable Functions, solved the problem of characteristic properties of bounded continuous functions and contributed to the establishment of the theory of real variable functions. 1902 Montpellier University, Dijon University three years later.