Maxwell's Silver Hammer

"Maxwell's Silver Hammer" is a song by The Beatles, from the "Abbey Road" album. Paul McCartney sings lead vocals. It was written by McCartney, though the songwriting credit is Lennon/McCartney.
Structure.
The vaudevillian-style song is about medical student Maxwell Edison, who uses his silver hammer to murder his girlfriend Joan, then his teacher, and finally the judge during his murder trial. Despite the grim subject matter, the song is bouncy and upbeat (a "happy song about a serial killer").
Meaning.
McCartney said in 1994 that it symbolizes the failures of life:
McCartney referred to the song when talking about his 2005 album "Chaos and Creation in the Backyard":
Recording.
After resuming to record the "Abbey Road" album, the Beatles began recording Maxwell's Silver Hammer at Abbey Road Studios on 9 July 1969. McCartney, Harrison and Starr taped 16 takes of the song, followed by a series of guitar overdubs.
The following two days the group overdubbed vocals, piano, Hammond organ, anvil and guitar. The song was completed on 6 August, when McCartney recorded a solo on a Moog synthesizer.
John Lennon later said, "I hate it...He did everything to make it into a single, and it never was and it never could have been."
George Harrison described it in 1969 as "one of those instant whistle-along tunes which some people hate, and other people really like. It's a fun song, but it's kind of a drag because Maxwell keeps on destroying everyone like his girlfriend then the school teacher, and then, finally, the judge." In 1977 Harrison was more candid, describing it as "so fruity" but added "we did a good job on it". 
The length of time it took to record the song created tension between the Beatles. Paul McCartney said: "The only arguments were about things like me spending three days on Maxwell's Silver Hammer. I remember George saying, 'You've taken three days, it's only a song.' - 'Yeah, but I want to get it right. I've got some thoughts on this one.' It was early-days Moog work and it did take a bit of time".
Personnel.
For the studio version of the song, the anvil was played by Starr; in the Beatles film "Let It Be", however, Mal Evans is seen hitting the anvil as the Beatles play the track.