English: An instrument which marks an intermediate step in the folding of the busine to make a double slide to draw out and lower the pitch. Here the busine is folded. The old single slide is retained with the whole S being drawn up and down as the slide closed and opened again. This drawing is a miniature by Taddeo Crivelli in the Borso Bible (See Hermann Julius Hermann, “Zur Gesch. d. Miniaturmalerei am Hofe der Este in Ferrara,” in Jahrb. d. Kunstsamml. d. allerhöchsten Kaiserhauses (Vienna, 1900), bd. xxi. pl. xiii.) of 1450-1471. The two upper joints defined by rings are clearly drawn of larger calibre than the lower folded portion, which has been drawn out to what would approximately correspond to the third position on the trombone lowering the pitch one tone. A single slide would require to be extended about twice the distance of the double or folded tube on the trombone to produce any given effect. This drawing of the sackbut must not be taken as showing the instrument in use in Crivelli's day; it is clearly retrospective, for sackbuts in a more advanced stage are not uncommon in works of art of the same century.