Watch the The Bowed String online guitar lesson by Angus Clark from Play in the Style of David Gilmour
Here's a further exploration of using a slide as a bow. I've tried steel and I've been stuck with glass (if I left my brass one at home), but it always comes back to the brass one. And I'm pretty sure I've had the same one for the last 30 years, and I don't think I paid for it. It was probably Jeff McErlain's, and I probably stole it from his room when we shared an apartment in Brooklyn.