"The Uffenbach brothers are in the Leiden University Library. Uffenbach is not able to continue his viewing of all the manuscripts in the Vossius collection, because the librarian prof. Senguerd had to leave. That afternoon the brothers visit the workshop of the oldest son of the recently deceased Johann Muschenbroek; the son was continueing his father's work in making scientific instruments with help by a younger brother. Uffenbach compares his work to that of Metz in Amsterdam. Mussenbroeck has a catalogue with instruments and prices, and Uffenbach describes several of these."