I finished the first L-shaped section of my garter stitch blanket, and weighed it to get an idea of how much yarn I had used. It weighs 15.9 oz., according to my handy digital kitchen scale. Just a smidge under a pound. And this piece represents about 1/8 of the blanket. This is going to be an 8-pound blanket!
I was scanning the pattern to put it on my ipad (a new trick I learned this past week -- knitting patterns on my ipad do not get crinkled or lost like paper patterns do!) and my eyes caught a note at the bottom of the page. This pattern was originally written in 1962 (older than me!), and the note at the bottom of the page (in The Opinionated Knitter, where the pattern is reprinted in its original form) says that the yarn used in the pattern used to have 30 more yards per 4 oz skein than it does now. It currently has 85 yards per skein, so as used in the original pattern, it would have been 115 yards, which means the Sheepsdown is actually very close in size to the Brunswick Aspen that I am using, that there isn't enough of to make the blanket with the yarn doubled. I found a size 15 circular needle and cast on 24 stitches to see what gauge I would get. It wasn't quite 2 stitches per inch, so I started calculating how many stitches I would need to cast on to get a 12" wide strip. Then I measured the bed, to see how big a blanket I would need to cover the mattress. I cast on 32 stitches, which would make about a 15" wide strip, but would have made a 5' x 7.5' blanket. Too long. My husband says, "well, you need enough to tuck under the mattress." No, we are not tucking a hand-knit blanket under the mattress.
The proportions of this blanket do not match any mattress, so I decided just to go back to the original 24 stitch cast-on and follow the pattern. If I want the blanket to be wider (more square), I can add a strip along one or both of the long edges. By this time, after much knitting and ripping, reading, calculating, and dithering, I realized that the gauge I'm getting with this yarn on size 15 needles is probably very close to the original pattern's gauge, based on the width of the piece so far, and the dimensions of the finished blanket in the pattern. So I'll have enough yarn to make the blanket, maybe even 2 of them! That is, if I can find the other 11 skeins. I looked yesterday, and I have 13 of what I'm fairly certain was 24 skeins. But I still like the two-tone idea. So ... we'll see.
Here's the new start, using a single strand of the yarn on size 15 needles, laid on top of the piece knit with doubled yarn on size 17 needles. Not much narrower, but it is not as thick. Still, I think it will make a nice, warm blanket.