Window frame with removable windows

Claim 1

IN A WINDOW FRAME ASSEMBLY, A WINDOW FRAME HAVING TWO OR MORE INWARDLY FACING WINDOW GUIDE CHANNELS LOCATED IN PLANES ADJUST TO AND PARALLEL WITH EACH OTHER AROUND THE INNER PERIPHERY OF THE WINDOW FRAME, THE SAID CHANNELS BEING FORMED BY INWARDLY PROJECTING FLANGE MEMBERS, THE VERTICALLY DISPOSED PORTIONS OF CERTAIN OF SAID FLANGE MEMBERS HAVING A PORTION OF THEIR LENGTH CUT BACK TO INCREASE THE HORIZONTAL WIDTH OF A WINDOW OPENING IN THE WINDOW FRAME, AN UPPER OUTER WINDOW MEMBER AND A LOWER INNER WINDOW MEMBER SLIDABLE VERTICALLY IN ADJACENT GUIDE CHANNELS, THE UPPER WINDOW MEMBER BEING REMOVABLE INWARDLY OF THE WINDOW FRAME FROM ITS GUIDE CHANNEL PAST THE CUT BACK PORTIONS OF ITS CHANNEL FLANGE MEMBERS AT THE LOWER END OF THE GUIDE CHANNEL, AND THE LOWER WINDOW MEMBER BEING REMOVABLE INWARDLY OF THE WINDOW FRAME FROM ITS GUIDE CHANNEL PAST THE CUT BACK PORTION OF ITS CHANNEL FLANGE MEMBERS AT THE UPPER END OF THE GUIDE CHANNEL, THE SAID GUIDE CHANNELS HAVING A SERIES OF APERTURES SPACED APART ALONG THEIR VERTICAL LENGTH, A PAIR OF SPRING LATCHES ON THE LOWER HORIZONTAL EDGE OF EACH OF SAID UPPER AND LOWER WINDOWS, THE SAID SPRING LATCHES ADAPTED TO ENGAGE IN SELECTED APERTURES IN THE SAID GUIDE CHANNELS, THE SAID LOWER WINDOW PREVENTING INWARD MOVEMENT OF THE SAID UPPER WINDOW PAST THE CUT BACK PORTION OF ITS GUIDE CHANNEL WHEN THE SAID UPPER WINDOW IS ALIGNED WITH THE SAID CUT BACK PORTION, AND A PAIR OF DETENT LATCHES ON THE UPPER HORIZONTAL EDGE OF SAID LOWER WINDOW, THE SAID DETENT LATCHES MAINTAINING THE SAID LOWER WINDOW IN SLIDING ENGAGEMENT WITH ITS GUIDE CHANNEL WHEN THE SAID WINDOW IS ALIGNED WITH THE CUT BACK PORTION OF ITS GUIDE CHANNEL.