Bell wasn’t the sole inventor of the telephone, but was the first to get it working effectively, and was a famous teacher of the deaf. His father took him, aged 15, to meet Wheatstone, a pivotal moment. Henry encouraged his sound-transmission experiments. Gray competed with him, accusing him of stealing his design, but in letters acknowledged Bell’s own prior work. Bell demonstrated his invention to Thomson, giving him some sets. Generous with money, he helped fund Michelson’s research. De Candolle, James, Draper, Longfellow, Holmes and Marconi — whom he invited to visit — were among his correspondents.