The origins of the Timpani
The History of the Timpani

Up through around the end of the 16th century, the drumhead of the timpani was generally tied to the shell by using a cord; but from the 17th century, timpani on which the drumhead was fastened to the shell using screws became common. The change to screws made it possible for the timpani to be tuned more easily, and timpani started to be used in orchestras and in church music performances in particular.

At the beginning of the 20th century, the screw timpani was the main timpani used. However, the disadvantage to this method was that the screws had to be turned manually to tighten, which meant that the pitch of the drum could not be changed continuously while playing. In the 19th century, many different devices were introduced to allow the pitch of the timpani to be instantly changed, but they were not widely used.
For this reason, the composers of the 19th century basically used the timpani at a fixed pitch, and thus had to write their music by allowing the players to take a break and retune the instrument as necessary. When it was necessary to play more than one timpani pitch at a time, a corresponding number of timpani were set up.
However, aside from those unique situations, composers generally called for the use of two timpani, each tuned in fourths (for instance, from G to C in the key of C major).

The use of foot pedals to change the pitch of timpani, rather than tuning by hand gained attention from the 20th century. The pedal timpani allowed the timpani pitch to be changed easily, as well as making it possible to play glissandos. Because of this, the role of the timpani in the orchestra has changed dramatically, and is now used even for playing solos, for instance.
Since the pedal timpani became used, making it easy to change the pitch, more music was written that included key changes in the middle of the song. The changes in the instrument, such as its use when playing glissandos by pressing the pedal to change the sound, have had an impact on the evolution of music itself.

Pedal timpani

Pedal timpani

Calfskin was used for timpani drumheads until the beginning of the 20th century.
From the 1950s, highly durable synthetic resin (plastic) began to be used. However, there are still some players who prefer timpani heads made of calfskin.