A harmonium, also known as a peti or baja, is a type of reed organ similar to an accordion. Invented in Paris in 1842, harmoniums were brought to India during the British occupation where they quickly gained popularity among Indian musicians. Today, harmoniums are used in a wide variety of traditional Indian music; however, they've made their mark in Western music as well. Generally favored by more experimental bands such as Radiohead, harmoniums have also appeared in classic Beatles tunes such as "Strawberry Fields Forever" and "Sexy Sadie." Harmoniums are fairly easy to play once you know a few basics.
Sit on the floor or at a table in front of the harmonium, and release the metal bar or latch on the side of the bellows. If you're right handed, release the latch on the left side of the bellows. Reverse these directions if you're left handed.
Pull out some or all of the main stops on the front of the harmonium. Stops look like little knobs, and their purpose is to direct air flow into the reed chambers in order to create different sounds.
Your harmonium may or may not have extra stops called drone stops, which produce a single constant note. These may also be pulled out.
Play notes on the keyboard using your stronger hand while pumping the bellows as needed with your weaker hand. Try to keep a steady rhythm when pumping the bellows.
Open and close the various stops to produce different sounds on the keyboard.
Listen to some traditional Indian harmonium music to get a feel for the style.
Drone stops may be set to any pitch, but usually they are set to A sharp, C sharp, D sharp, F sharp and G sharp.
Don't pump the bellows without playing the keys, and never pump the bellows without first opening a few stops.
Always close all stops and lock the bellows when you're finished playing.
Keep your harmonium away from water and direct sunlight.