Down to Mirth is a 1959 Casper the Friendly Ghost cartoon.
Summary[]
Casper attends a science convention. A mad professor demonstrates his new anti-gravity machine. He floats kangaroos and lions into space. It's up to Casper to stop the evil professor and get the animals back down.
Plot[]
A mad scientist invents an anti-gravity machine, and is using it to create havoc on earth. Casper, the Friendly Ghost, gets involved with the mad-man and eventually forces him to destroy the machine and bring earth back to earth.