STAIR, a succession of steps affording means for a person on foot to get from a lower to a higher level. There are two main forms of this, one composed of a series of solid blocks generally touching one another at one edge, as when a series of squared stones are built into a wall at either end, their small surface of junc tion merely steadying them; and the more corn mon sort, in which two sloping beams, planks or metal girders, called string pieces or strings, support a series of horizontal planks, slabs of marble or slate, or plates of metal called treads. The above are the essentials of a stair. The riser which stands for the vertical distance from one tread to another may be left open, or may be filled by a light board, a piece of open work cast iron or the like. In the case of a stone step the tread is the uppermost surface and the riser the front — the surface turned toward the person who is ascending.
There is a marked distinction between the straight and the winding stair. In a straight stair all the steps are called fliers and the tread of each is of the same width from end to end. In the winding stair the steps are called winders and the treads are much narrower at one end than at the other. The typical winding stair is the spiral or corkscrew stair (in French called a folsmacori, snail-like). These are commonly into nto round towers, the walls of which sup port the steps, but it is feasible to build them of wood or iron, and in modern libraries and other places of storage, very light spiral stairs are built for easy access to balconies, galleries and upper floors, as in the stack-room for books or other place of deposit or storage.
A stair may be made up of several short stairs called usually flights. Thus in the case of a rather lofty story, there may be one or even two landings in the height from floor to floor, and, therefore, two or even three flights. If these landings give to the stair a change of direction of 90 degrees, so that a person ascend ing and going northward suddenly turns east ward or westward, the platform is called a quarter-pace (sometimes quarter-space). If the change of direction is of 180 degrees, the per son ascending reversing his direction as from north to south, the word half-pace (half space) is used. A combination of dies methods is also used, as where a platform is associated with some winders; the platform being then nothing but a tread much wider than the others. This is a very objectionable plan, as being dan gerous for persons not acquainted with the stair.
The height of the riser and the width of the tread are matters of great importance. Rules exist for fixing these, and it is generally con sidered that the riser and tread must be taken together. Thus, if it be held that each tread and-riser should measure 18 inches, then the riser may be inches high, the tread inches wide. This is often expressed by the formula, a riser inches, a run of inches, or by the phrase, the rise and run are to each other as to 11%. In modern build
ings of no great cost or elegance the stairs are often very much steeper than this; and the proportions may even be reversed, or nearly so, in the case of a flight rarely used, as from the top floor to the roof.
The stair is often an architectural feature of some importance. In the interior a large hall is sometimes devoted to it, and the stair itself is a principal part of the decoration, perhaps passing along three sides of this hall, seeming to cling to the wall as it ascends, leaving be low an open floor of considerable size which may be treated more or less as a sitting-room, and at the top communicating with a gallery. This gallery may be a highly architectural mem ber, being treated with columns to support the roof. The objections to this treatment of a stair are the great amount of space occupied and the opening of so much of the interior to drafts of air and to ready communication of fire. It should only be used where the building is wholly fireproof. It leads to great expense in building the stair of marble, lining the walls with the same or an equally costly material and roofing the whole with an architectural dome or coved ceiling with or without a sky-light. The tendency in recent times is to use elevators in buildings of all kinds, public and private, and in consequence of this the stair seems to be considered sometimes a mere piece of utility and for that purpose made as compact as pos sible; while in another building not more costly and splendid it will be treated in the way described above. It is worthy of notice that any building in which it is expected to give stately entertainments, the stair-case, or hall, which encloses the stair, will be treated in a more stately way, and this because of a tra dition that the persons of a large assemblage will seek the halls and stairs, perhaps for more space, perhaps for fresh air. Thus, in an opera house, the stair is a very important feature.
Out-of-door stairs are seen on city tene ments and apartment houses as fire-escapes, but they do not often exist in connection with classical or neo-classical architecture. They have great picturesqueness of effect and are associated with media-val architecture — both northern and southern — and with the rough wooden buildings of Switzerland and Tyrol.
The term stair is not often used to cover the broad flight of steps leading up to a portico, nor for the steps of a front door when they do not exceed 10 or 12 in number; nor yet for those in a terraced garden. For such out-of door flights of steps the French term person may be used and is perfectly descriptive of the thing; no correlative term exists in English ex cept the local term used in New York City and vicinity: stoop.