Yolland Ice & Fuel Company, phone 5100. Note the tag. There's no way of knowing whether this particular ice pick actually penetrated anyone's orbital, but if it wasn't this one it was probably one very like it. In his quest for something that wouldn't snap when he hammered it in, Walter imitated Egas Moniz, who had been inspired by an apple corer, and went rummaging in the kitchen drawer. Let's face it, he would have jumped off a bridge if Egas Moniz had done it first. "What's 'cannonball' in Portuguese, Professor?"
See an actual photograph of the pick in question here. Note the pencils. They don't let you take pens into the Special Collections reading room.