Which inventor demonstrated an early telephone at Philadelphia’s 1876 Centennial Exposition?

Alexander Graham Bell demonstrated an early telephone at Philadelphia’s 1876 Centennial Exposition.

Bell’s exhibit was part of the fair’s displays of new technology. His telephone was arranged with instruments at opposite ends of Machinery Hall, allowing visitors to hear transmitted speech. The demonstration brought the invention international attention.

Emperor Pedro II of Brazil was among the prominent visitors who showed interest in Bell’s work. The Scottish physicist William Thomson, later known as Lord Kelvin, also examined the device and praised its significance.

Bell had received U.S. patent 174,465 on March 7, 1876. The telephone’s history also involves Elisha Gray, whose competing work led to later disputes over priority, but the Centennial Exposition demonstration is associated with Bell.