"Pow R. Toc H." is an instrumental track on Pink Floyd's first album, The Piper at the Gates of Dawn. It runs four minutes and 26 seconds, and is track two on the original release (1967) and track five on the 1987 release.
Okay, I'll get right to it: it's one weird fuckin' song. It begins with a mystical vocal "tchh tchh" but quickly breaks into some screeching, and then into simple rhythmic drumming on low tomtoms with voices screeching and saying "a-doi doi". The voices fade out and a seemingly improvised one-handed piano part starts. The piano stops after a minute or two with a cymbal crash and an acoustic guitar part, and the "a-doi doi" voices appear again. The voices and piano quickly fade out and the guitar quiets down as an airplane-like whining/droning begins, and the drumming is focused on the cymbals. A synthesizer enters with simple chords and the airplane whining dies down, and what might be a credible beat starts to emerge as an electric guitar is sporadically picked and the cymbals are frequented regularly. The hubbub dies down to the original simple drum part on the tomtoms, and after a few seconds the "tchh tchh" reappears. Before the song has a chance to end, a vibrato-ing guitar and more screechy voices pop in, and the drums finally wrap it up.
A very weird, classic Syd Barrett-type song: but in the composition way, not in the crazy lyrics way (like "Bike," the last track an the 1987 album).
Anyway, the song was built off of Roger Waters' bassline, which is barely audible. Live, the song was started by Barrett saying into the microphone "badoom...tchh tchh", and the band would jump in with heavy improvisation, sticking only to the basic idea of strange screeching vocals and a jungle-like sound.
The name means doesn't mean anything; many people think of it as "power toke" or "power tokage". I've always thought of it as "power torch," and I'm not the only one. The name comes from an interdenominational Christian fellowship called "Toc H" founded in 1915 in Flanders, and apparently Barrett stuck "Pow. R" in front of it because it sounded good (and "power" is a cool word).
If you're curious, there are a few websites where you can download a live performance of this song, notably www.syd-barrett.it.