Who invented the whisper dish?

Expert Answers

An illustration of the letter 'A' in a speech bubbles

The "whisper dish," better known as a form of parabolic lens or microphone, has been around in theory for centuries. The ancient mathematician Diocles first theorized on parallel beams in his book On Burning Mirrors. Archimedes supposedly used parabolic reflectors on the Roman fleet at the Siege of Syracuse more than 2000 years ago. More recently, James Gregory, inventor of the Gregorian telescope, wrote about paraboloids in Optica Promota (1663). Isaac Newton disregarded the use of parabolic properties on his own spherical Newtonian telescope. Older lighthouses also used parabolic mirrors to project lantern light into a beam before being replaced by fresnel lenses in the 1800s. 

Approved by eNotes Editorial Team