Over at H&FJ, the H talks about the &.
As both its function and form suggest, the ampersand is a written contraction of "et," the Latin word for "and." Its shape has evolved continuously since its introduction, and while some ampersands are still manifestly e-t ligatures, others merely hint at this origin, sometimes in very oblique ways.
He goes on to describe several ampersands they've designed for their typefaces. When designing the ampersand for Silkscreen, I came up with a solution that many continue to dislike:
If you're logged in to Flickr, you can see it action at a more appropriate size in the "prints & more" label above a photo. The symbol is basically a capital E with a vertical line through the middle...an e-t ligature that's really more of an overstrike. I fashioned it after the way I hand-write my ampersand, which I got from my dad's handwriting1. I don't know where he got it from; it's not a common way to represent that symbol, although I did find a few instances in the list of fonts installed on my computer.
I didn't think about this way at the time, but the odd ampersand is one of the few distinguishing features of Silkscreen. There's only so many ways you can draw letterforms in a 5x5 pixel space so a lot of the bitmap fonts like Silkscreen end up looking very similar. The ampersand gives it a bit of needed individuality. (The 4 is the other oddish character...it's open at the top instead of diagonally closed.)
[1] Now that I think about it, I borrowed several aspects from my dad's handwriting. I write my 7s with a bar (to distinguish them from 1s), my 8s as two separate circles rather than a figure-eight stroke, and my 4s with the open top. Oh, and a messy signature. ↩