‘Engineer Guy’ Bill Hammack is the professor you wish you had. He’s a member of the faculty at the University of Illinois and the creator of a series of videos that explain technology.
This set of videos take a look at Albert Michelson’s Harmonic Analyzer – a nineteenth century mechanical computer that performed Fourier analysis by using gears, springs and levers to calculate with sines and cosines—an astonishing feat in an age before electronic computers.
Fourier analysis is the study of how complex functions can be broken down into simple ones. In the area of sound and synthesis, Fourier analysis can be used to break down any periodic sound into component sine (and cosine) waves. And, going in the opposite direction, sine waves can be combined to create complex sounds.
This is now done with computers, but 100 years ago, it was done with machines.
In the first video, above, Hammack introduces the Harmonic Analyzer. In the second video, he looks at how the machine can be used to synthesize complex waves:
in the third video, Hammack looks at using the machine to do analysis:
The last video dives into the technical details of how the Harmonic Analyzer is configured: