The mighty rulerphone

Every New Years Eve, Miss Hathorn and I meet up with our friends Isambard and Nevsky with the aim to create something before dinner hits the table. In 2003 it was an Automaton, in 2004 Masks, which I will publish in some future post, but in 2005 it was to make a musical instrument on which one could play Auld Lang Syne by midnight.
Here is my Instrument, tuned to the Key of A.
I figured, by twanging the rulers along the table edge, that a length difference of 30 mm would result in one octave pitch shift, so the whole rulerphone, which has a range of 1 octave and 1 note needed to have 35 mm slope build into it to make all the rulers come to the same point at the front.
And, it all worked and we made sweet moosic...