the slide stays became tubular. On many modern reproductions round slide stays are much more comfortable to play and easier to make. A loose connection between the bell stay and the bell is thought key to a resonant bell, and thus a better sackbut sound. Original instruments have a hinge joint (a looser connection helped imperfect slides slide). Modern copies with a tuning slide in the bell can need more support for operation of the slide, so either an extra stay by the tuning slide is provided or a joint without play in only one axis is employed. The original way to make the slide tubes was to roll a flat piece of metal around a solid cylinder mandrel, and the joining edges soldered together. Modern manufacturers now draw the tubes. They also tend to have stockings, which were only invented around 1850. In addition, modern made slides are usually made of nickel silver with chrome plating, giving a smoother finish and quieter action than simply the brass that would have originally been used. The water key was added in the 19th century, but modern reproductions often have them. Pitch Until some time in the 18th century, the trombone was in A and the pitch of that A was about a half-step higher than it is today—460–480 Hz. There was a transition around the 18th century when trombones started to be thought of in B at around 440 Hz. This change did not require a change in the instrument, merely a new set of slide positions for each note. But it does mean that the baroque and renaissance repertoire was intended to be played at the higher pitch. There are many examples of evidence for this: Fellow church instruments that are fixed pitch—cornetts and organs—were pitched at approximately A=460–480 Hz ("Chorton") across Europe in the Renaissance and baroque eras. High pitch is also seen in Renaissance wind bands. Aurelio Virgiliano's Il dolcimelo (c. 1600) teaches trombonists that first position gives A, E, A, C, E and G. In 1687, Daniel Speer's Grund-richtiger concurs with these notes for the slide all the way in (while describing pushing the slide out a bit to get the C). Praetorius describes an alto in D, tenor in A, and bass in D. The tenor trombones that survive are pitched closest to B at A=440 Hz, which is the same as A at A=466 Hz.