We have an old skylight in our bathroom. At the base of the shaft are two windows that open like doors. The top of it is an old heavy glass window which sits unsecured. It seems they relied on its weight to keep it in place. Does not appear to have ever had hardware to secure it in place. House was built in 1929. The vent is next to the window in one of the upper walls, it is large (about 24" square)and has only an old fixed screen covering it on the inside. It gets very dirty and it is hard to clean as that requires removing the windows at the bottom of the shaft. What can I do to modernize this? It seems to me now to be like a chimney sucking heat out of the house, though you can close the windows at the bottom of the shaft. Any ideas would be appreciated. I am thinking we should mount a fan in it somewhere. Thanks!