About the Slide Trumpet
No slide trumpets survive from the Middle Ages or Renaissance. However, several paintings, woodcuts, and sculptures depict what are conjectured to be slide trumpets. One of the earliest of these, and one of the most compelling, is the famous triptych by Hans Memling dating from the 1480s. It has been titled "Angel Musicians" and includes images of angels playing a wide variety of instruments. Three of these are trumpets. (One is a straight trumpet, and the other two are divided into three yards by two bows.) In all three examples, the angel has one hand holding the mouthpiece against the lips, while the other hand looks as if it is gently pushing or pulling the body of the instrument. A second example is a sculpture from Himmelkron Monastery. Again, the angel is using one hand to hold the mouthpiece while the other hand delicately holds the rest of the instrument. A third example is a woodcut from J. Rodler, "The Origins and Development of the Tournament in Germany" from 1532. It pictures two musicians playing trumpets. Again, one hand is holding the mouthpiece against the lips, while the other hand is holding the instrument. Several other woodcuts depicting what are conjectured to be slide trumpets survive from the 16th and 17th centuries.
One slide trumpet from the early baroque survives in the musical instrument museum in Berlin. It was created circa 1650 and was obtained by the museum in 1890 from the Wenzelskirche in Naumburg. This trumpet is somewhat similar to the ones pictured in the renaissance.
John Webb of London created a reconstruction of such a trumpet. It is pictured on this page. The slide is part of the leadpipe and has a range of several semitones. To play the instrument, one hand is used to hold the mouthpiece against the lips, and the other hand moves the rest of the trumpet, just as pictured in the Memling painting. From my experience with the instrument, the slide does not create a glissando. Rather, it allows the pitch of the instrument to be changed, between blowing notes, without having to resort to inserting or removing a crook.
Evidently, Slide trumpets were used throughout Europe. In Germany they were known as zugtrompete, while in Italy they were called tromba da tirarsi. The slide trumpet underwent further development in England, where it was given a double slide like the sackbut. The instrument was known as the Flatt trumpet. Purcell's Music for the Funeral of Queen Mary is in a minor key and requires the use of a quartet of such instruments.