
It’s a crossbreed between Verdana and Baskervillle: Verdeville sans
It’s public domain, by the way, if you can think of a use for it.
Update:

I also corrected the last two glyphs (254 and 255), which I’d got mixed up, so now it has lower case thorn and dotted lower case y in the right places, for the benefit of Icelanders and whoever it is that uses the dotted y.

Why is the image not showing up in my dashboard view? Is it because I had to make this a “text post” to get a big image? Why do I have to use external hosting if I don’t want my images resized to 500px? Why is it that if you use a URL as the source for a photo post, tumblr makes its own copy and resizes it? It’s like an aunt who sometimes gives you free stuff but also comes round to your house and tidies things up without asking, and then all the pans are in the oven and your clean clothes are in the laundry basket and she’s thrown away that experiment you were doing because it looked messy.