Peugeot diamond frame 1891

This very nice early Peugeot is for display in the Musee de l' Art et d' Industrie in St. Etienne. The bike has some nice details, starting with the frame: an early diamond frame, without seat tube. But also look at:
- the interesting way to adjust and secure the top head ball bearing
. the system for chain tensioning at the crank
- the extra holes in the rear mudguard puzzle me. So, it is possible to place the mudguard a bit more 'forward'. But what's the use?

Serial number 10337 is inscripted on left side of the head tube. The Musee de l' Art et d' Industrie states it was built in 1891. I think that is a good guess, looking at the ball head and other details.
I made a page mentioning alle featured Peugeot bicycles and more info on serial numbers.