Editing Microphone (section)

=== Liquid ===
{{Main|Water microphone}}

Early microphones did not produce intelligible speech, until Alexander Graham Bell made improvements including a variable-resistance microphone/transmitter.  Bell's liquid transmitter consisted of a metal cup filled with water with a small amount of [[sulfuric acid]] added. A sound wave caused the diaphragm to move, forcing a needle to move up and down in the water. The electrical resistance between the wire and the cup was then inversely proportional to the size of the water meniscus around the submerged needle.  Elisha Gray filed a [[Patent caveat|caveat]] for a version using a brass rod instead of the needle.{{when|date=February 2019}}  Other minor variations and improvements were made to the liquid microphone by Majoranna, Chambers, Vanni, Sykes, and Elisha Gray, and one version was patented by [[Reginald Fessenden]] in 1903. These were the first working microphones, but they were not practical for commercial application.  The famous first phone conversation between Bell and Watson took place using a liquid microphone.