They're for height more than distance.
Picture your mum in a cannon.
Point it up and she's liable to fly really high then fall on you. If you point it more forward, she'll rocket (screaming) over the trees. One of these situations is really cool and funny.
(
Syncubus Yarr! Ye'll be walking Planck's Constant! [GMT-5],
Fri 20 Jan 2006, 1:28,
archived)