Christy - Eldredge merges with a few other companies and formed National, I think this was the late 1800's. So unless you have a very early eldredge, it's goihng to be made by the same company as your Bartlett. If that is the case, and they are both VS machines, they'll take the same shuttles and most likely the same needles.
They should also take the same attachments except for the plates, since your Bartlett has the wide plate.
Let us know what you are missing with your Eldredge - it's likely it won't take much to get them both up and running.