Wodehouse's Trayser harmonium, acquired in 2006 is her grandest to date. This instrument was built in 1875 by Phillippe J. Trayser & Cie, a German builder. The harmonium as an instrument was developed primarily in France (the Trayser is built according to French design). By the second half of the nineteenth century the harmonium had evolved into a sophisticated instrument. Two foot pedals pumped the bellows and the more expensive models had two keyboard manuals (each encompassing a range of five octaves) with up to thirteen stops or more, including tremolo and one or two knee-pedals to control volume. It was used in churches that could not afford a pipe organ and in the home for music making alongside the piano. Many nineteenth-century composers (Saint-Saens, Berlioz, Franck, Bizet, etc.) wrote serious music for the instrument. Unfortunately, just when the harmonium had reached it's technical peak, the piano easily overtook it in popularity.

The harmonium differs from the reed organ in that the air is blown out through the metal reeds (pressure). The reed organ produces sound by sucking in the air through the reeds (suction). As a result, harmoniums are generally louder and more focused in sound.

Trayser specifications:

• 20 stops, 5 1/2 sets of reeds
• 2 manuals (61 notes each, C to C)
• Split point - E above Middle C and down, lower keyboard, F above Middle C and up,upper keyboard
• Forté - opens up bass half of organ so it will be louder
• Sourdine - muted 8-foot stop in bass, upper keyboard
• Voix humaine - soft 8-foot stop with slight vibrato, upper keyboard
• Basson - basic 8-foot stop in bass, upper keyboard
• Clairon - trumpet-like 4-foot stop in bass, upper keyboard
• Bourdon - 16 -foot stop in bass, lower keyboard
• Cor Anglais - basic 8-foot stop in bass, lower keyboard
• Percussion (strikes brass reeds) - one stop each for bass and treble
• Expression - opens bellows so that softer effects can be obtained through different foot-pedaling technique
• Grand Jeu - opens all stops to play with exception of Voix humaine and Voix celeste
• Manual Coppel - manual coupler
• Double Expression - sudden blast of air for accents
• Flute - basic 8-foot stop in treble, lower keyboard
• Clarinette - 16-foot stop in treble, upper keyboard
• Flageolet - Trumpet-like 4-foot stop in treble, upper keyboard
• Hautbois - 8-foot stop in treble, upper keyboard
• Voix céleste - 8-foot stop with slight vibrato in treble, lower keyboard
• Tremblant - 8-foot strange tremolo, upper keyboard
• Forté - opens up treble half of organ so it is louder