One of three in my shop, this is antique ecclesiastical sheet music in Latin, from earlier centuries, commonly known as an "antiphonal". These are normally seen as hand painted manuscripts on vellum (animal skin). The present example (17 1/2" by 13 1/2") is a rather typical example, with red bars, and brown/sepia lettering and notes. Condition is good considering the advanced age of the sheet, with overall wrinkling/rippling. See the net for more information on these early music sheets, which were an important part of religious music, principally in Spain, where Benedictine monks would create these. All photos taken through detail-dulling non-glare type glass.
Antique music double sided antiphonal on animal skin circa 17th century