The first Mobility Bag?

I find mobility bags interesting.

It is certainly a niche part of the market, and one category that still has quite a bit of room left for innovation. Despite the push for multipurpose gear and lighter base weights in the UL community they still don't seem to hold much market share.

I'm also very interested in the origins of things. Even focused on the relatively young outdoor gear market, this is seldom an interest that I can exercise with any certainty, but in this case I might have caught a break:

I'm not sure where I first found this picture, but the only source I can find currently is an article over at Science in the Cold War. According to the caption on their version of the photo it hails from 1959, at Ladd Air Force Base in Alaska. Its easy to see that the older canvas shelled feather bag was employed for this experiment, which is made easier by its center zip, which modern mobility bags seem to be largely returning too.

I think it safe to say for the moment that this is the oldest example of a modern sleeping bag with arm and leg openings, so for now at least I'm declaring it the first true mobility bag.