Go back out so you're facing the bathroom. If only you had something that could hold water. It looks blank, but if you click on the opening, you find out that it used to hold water. Go to the Ancient Egypt exhibit and unlock the door (yellow key). You can evidently find and replace the rail, but I haven't figured it out and you don't have to do it to escape the museum.) Leave the exhibit - there's nothing more for you here. Use the silver key to open it up, and take the lantern on the left podium. Let's go to the Gold Mining exhibit first.
