WINDOWS 105 



that they do not penetrate the interior of the box-frame, where they 

 might interfere with the balance weights. 



A solid-frame window is similarly fitted. Sometimes, however, the 

 solid frame is entirely dispensed with, its place being taken by 

 the posts A, A, and the rails B, B, and the sash being hinged either to the 

 lower B rail, or to one of the A posts. 



Lighting Area to be provided in Windows. — Local Government Board 

 Regulations in England require that the total area, clear of the sash 

 frames, of the window or windows in every habitable room of a domestic 

 building, shall be equal to at least one tenth of the floor area of such 

 room; and every such window must be constructed so that one half, 

 at least, may be opened, and that the opening may extend in every 

 case to the top of the window. 



