The Sound Of Tubes, Tape & Transformers.
By Hugh Robjohns at Sound On Sound
http://www.soundonsound.com/sos/feb10/articles/analoguewarmth.htm
Harmonic Analyzer
Analog spectrum analyzer by Albert Michelson circa. 1897
Documentary by Bill Hammack
Paper by Bill Hammack, Steve Kranz, and Bruce Carpenter
http://www.engineerguy.com/fourier/pdfs/albert-michelsons-harmonic-analyzer.pdf
Analog computers
John Whitney in “Computers: Challenging Man’s Supremacy”.