margin–light (1), narrow strips of glass, sometimes coloured, occurring in sash–windows of the early nineteenth century.
margin–light (2), tall narrow window on both sides of a door.
Interestingly, the margin lights extend upwards to the full height of the door and its fanlight. Above that the central window is flanked by a reprise, and has a cornice to distinguish it from the general fenestration. The blind windows at top floor level clearly mask the line of the roof slope.
marigold window, see rose window.
meeting–rail, the combination of the bottom rail of the top sash and the top rail of the bottom sash, in a sash window.
misting, a phenomenon that occurs in poor quality or badly fitted double glazing sealed units.
When two sheets of glass are formed into a double–glazing unit the success of the operation depends on the quality of the polymer edge seal that creates the air gap between them. In some circumstances sunlight can cause degradation of the seal; in others the seal may be broken due to improper fitting combined with movement stresses. In either case moist air can enter and condense to form a permanent semi–opaque surface coating. The cure for this is replacement. Many sealed units do not last beyond ten years, with an expected maximum of thirty years.
mortise, mortice, a slot cut out of a piece of timber in order to receive a tenon.
moulding, a continuous contoured profile carved in wood or stone, cast in metal, or formed in terra cotta or fibrous plaster, serving a variety of architectural and practical purposes.
See astragal, bead, cavetto, cyma recta, cyma reversa, fillet, ovolo, reeding, scotia, torus.
mullion, an upright timber post or similar stone member dividing a window into two or more units or lights, each of which may be further divided into panes.
The word ‘munnion’ appears alongside mullion, as an alternative form in Nicholson’s Practical Builder and Workmen’s Companion, 1823.
mullioned sash, an early form of window divided by a central mullion, with sashes either side.
In the earliest windows of this type the top sash was fixed. See Note 2 Part 2, for the development of the sash window.
multi–foil window, a window or window–surround edged with lobes or leaf–like shapes separated by cusps.
muntin, US term substituting for UK mullion or astragal (glazing bar).
In the UK a muntin is nowadays a vertical member in a door or wooden panel. The word is a corruption of ‘montant’, indicating ‘rising’ in this context. Nicholson’s Practical Builder and Workman’s Companion, 1823, defines ‘muntins or montants’ as ‘the vertical pieces of the frame of a door between the stiles’.