# Inventions on Prime Numbers

Today’s project was a two-part invention in two tempi. The tempi are drawn are from the prime numbers 139 and 97. This lasts about about a minute and  uses a harpsichord sound here.

The upper part is at the speed of 139 beats per minute; the lower part is in 97 beats per minute. This invention is, then, one cycle through this complex tempo relationship based on two prime numbers. An approximation of this ratio (139:97) in simpler terms would be about 10:7.

One things I learned in today’s experiment and study is that the “Golden Mean” reared its head in a very clear manner. It has to do with the instances where there would be two beats of Part A (139) fit between 2 beats of Part B (97). On my notes  I colored the block green when this happened. What shakes out is a pattern of 3-2-2, 3-2-2, 3-2-2 which drifts to the right. At the GM, the correction to this occurs, giving us a 3-2-2-2. Ultimately, musically, this signals “crunch time” as the two orbits “flatten” net to each other somewhat. I utilized this point of interest in the music by giving both parts brief chromatic wedge figures, fattening the texture, and followed this point with a pedal point and recap of sorts.

Enjoy!

EH – 7/23/16