Emmett, I read that book, too! You're quoting Jules Verne From the Earth to the Moon.
6 seconds sound clip from the Back to the Future Part III movie soundboard.
You can hear this line at 01:04:07.561 in the DVD version of the movie.
Quote context
[...]
- Listen to me. I feel like I'm teaching school.
- Definitely. Although not for 84 years and not on trains.
- That they break the pull of the Earth's gravity, and send the projectile through outer space.
- Emmett, I read that book, too! You're quoting Jules Verne From the Earth to the Moon.
- So do I.
- You couldn't have read that when you were a boy. It was only first published 10 years ago.
- Oh, yes. Well, I meant it made me feel like a boy.
- I never met a woman who liked Jules Verne before.
[...]