On March 10, 1876, three days after his patent was issued, Bell succeeded in getting his telephone to work, using a <answer>liquid</answer> transmitter similar to Gray's design. Vibration of the diaphragm caused a needle to vibrate in the water, varying the electrical resistance in the circuit. When Bell spoke the famous sentence "Mr. Watson—Come here—I want to see you" into the <answer>liquid</answer> transmitter, Watson, listening at the receiving end in an adjoining room, heard the words clearly.
What kind of transmitter did Bell put in his telephone?
liquid