gauss cannons and calculus problems

I need to look more into making my own gauss cannon/rifle. That would be really neat. Here's a little homemade toy version: Gauss Rifle

Also, I stumped my Calculus 3 professor when I asked whether two lines in 3d space would be considered perpendicular if they didn't intersect, but their base vectors where perpendicular. Guess I'll have to ask google and then Ask Dr. Math.