Composed ca.1760 and reproduced in facsimile in two volumes. 21 duos, with both parts in the 1st horn book, and 3 trios, with the 3rd horn part in the 1st horn book. The second book is the 2nd horn part. Four composers are indicated on the title page, by last name only, and there is no indication in the music who these men were or which pieces they wrote.