STAIRS AND STAIRCASES.

115. STAIRS and STAIRCASES are made of various forms, but convenience, safety, strength, and simplicity, are the most essential characters of a good one. In a convenient house, the place of the staircase should be easily recognised, and yet without its being exposed to the entrance. The ascent should be easy and regular; and winding steps should be avoided, if possible. There should be landings at convenient distances, a rule which is too frequently neglected in modern houses; Alberti, in his Architecture, says, the best architects never put above nine steps to one flight.

The rail should be of a proper height and strength for safety, and the stairs should be firm and well supported.

Definitions of the Parts of Stairs.

116. By Stairs we mean an assemblage of steps, so formed and united, that, by walking on them, we ascend or descend from one height to another.

117. The surfaces on which we set our feet are called TREADS; and these, for the convenience of walking, are set at equal distances, and parallel to each other.

118. In order to give a solid appearance to the whole, every tread has a vertical piece beneath it, called a RISER. A riser and tread, when fixed together, forms what is called a STEP. 119. The inclosed space in which the steps are fixed, is called the STAIR-CASE.

each step is commonly supported by a wall of the staircase.

One end of

120. If the ends of the steps terminate so as to leave an open space in the centre of the staircase, the space left open is called the WELL-HOLE. The form of the well-hole is sometimes square, or rectangular, but most frequently it has parallel sides and circular ends.

121. Stairs that have a well-hole, or hollow in the centre, and the steps supported by their ends in the walls of the staircase, are called GEOMETRICAL STAIRS.

122. The front edge of the tread is called the NOSING, and is usually rounded, or both rounded and moulded. The line which may be drawn to touch the nosings of a series of steps is called the LINE of NOSING.

123. When the treads of a series of steps are each parallel, such a series of steps is called a straight flight, and the steps are denominated FLYERS.

121. When the treads of the steps diminish in breadth towards the central part of the staircase, the steps are called WINDers.

As the ends of the steps, called winders, generally terminate upon a surface which is perpendicular both to the risers and treads, the surface on which they thus terminate is commonly called that of a cylinder; though only strictly so when the well-hole is circular.

125. When the tread of a step is so broad as to be equal to two or more of the other steps, and situated between floors, it is called a landing, or RESTING-PLACE.

126. If the resting-place be a square, or, if the riser to a resting-place be at right angles to the riser from it, the resting-place is called a QUARTER-SPACE or Quarter-pace.

127. When the breadth of the resting-place extends across the staircase, or the riser to the resting-place be parallel to the riser from it, the resting-place is called a HALF-SPACE or HALF-PACE. 128. Half-spaces and quarter-spaces, on a level with floors, are properly called landing-places.

Proportions of the Parts of Stairs.

129. THE breadth of the treads of the steps of common stairs is from nine to twelve inches. In the best staircases of noblemen's houses and public edifices, the breadth ought never to be less than twelve, nor more than fifteen inches; the latter is the breadth of the treads of the stairs of the Palace at Hampton Court.

130. A step of greater breadth requires less height than that of a less breadth; and the first person who attempted to fix the relation between the height and width of a step, upon correct principles, was, we believe, Blondel, in his "Cours d'Architecture.” If a person, walking upon a level plane, move over a space, P, at each step, and the height which the same person could ascend vertically at one step with equal ease, were H; then, if h be the height of a step, and Ρ its width, the relation between p and h must be such that when p=P, h=0; and when h=H, we must have po. These conditions are satisfied by an equation of the form

h=H (1-3).

Blondel assumes 24 inches for P, or the step a person can make with ease on a level plane, and 12 inches for H, or the height a vertical step can be made with equal ease; and, putting these numbers for P and H, in our equation, it becomes h=(24-p), which is precisely Blondel's rule. We do not think that the rise, which is equal to a level step of 24 inches, is more than 11 inches, but it would be difficult to ascertain the ratio exactly, and the above are so near, and agree so well with our observations on stairs of easy ascent, when the breadth of the tread includes the nosing, that they may be taken for the elements of a practical rule. Hence, according as the tread p, or the rise h, is given, we have h=24; or p=24— 2h. Thus, if the height of a step be six inches, then p=12, and 24-13=6, the rise for a step that has a tread of 12 inches, including the nosing. And, as the nosing ought not to exceed an inch, we have these general rules.

131. To find the proper Rise for the Steps when the Tread is giren.

From 23, substract the breadth of the tread in inches, and half the difference will be the rise. Thus, if the tread be 12 inches, then

23

12

2) 11

5 inches, the rise required.

132. To find the proper Tread when the Rise for a Step is given.

Substract twice the rise from 23, and the remainder will be the proper width for the tread

Thus, if the rise be 5 inches,

23

2 x 5 = 10

13 inches, the tread required.

Again, if the rise be 7 inches, then,

23

2 x7 = 14

9 inches, the tread for a step with a rise of 7 inches.

133. Before we set out the stairs in a building, we must consider the height of the story, and determine upon the height or rise of the steps; which being done, we must take the height of the story in inches, and divide the number of inches in the height of the story by the least rise proposed for a step; if the result be fractional, divide the height of the story by the number, neglecting the fraction, and the result will be the exact height of the rise. Thus, for example, suppose the height of the story to be ten feet four inches, and the height of a step to be not less than seven inches, how many steps will be required in order to ascend to the given height? Here (10 ft. 4 in.) × 12 124 inches. Now, 124=17%, which, neglecting the fraction, is the number of steps required; and 24=75 inches, the height of the rise. But, if there be no winders in the stairs, an even number of steps will be more convenient than an odd number: therefore, either eighteen or sixteen may be adopted; if we must have sixteen, 7 inches; which may answer very well: but, if we are still confined for room on the plan, we must be obliged to have recourse to winders.

17

17

124

134. The breadth of a staircase may be from five to twenty feet, according to the destination of the building; but if the steps be less than two feet four inches in length, they become inconvenient for the passing of furniture, and such narrow stairs should be avoided even in small houses.

135. When the height of the story is very considerable, resting-places become necessary. In very high stories, that admit of sufficient head-room, and where the plan or area for the stairs is confined, the stairs may make two revolutions in the height of the story; that is, in ascending or descending, we may go twice round the newel or well-hole; and this becomes necessary, otherwise the steps would be enormously high, or extravagant floor room must be allowed for the stairs.

As grand and principal staircases require broad and low steps, they therefore require to be numerous, and admit of only one revolution in the height of the story; the plan being always proportioned to the height of the building.

136. It may not be amiss to give an example here for a principal building, in order to show the number of steps both in the grand and in the common staircase.

For this purpose, suppose the story of a house to be sixteen feet high from floor to floor, the height of the steps of the servants' staircase to be not less than seven inches, and that of the grand staircase to be not more than six inches.

Now the height of the story reduced to inches is 192, and first dividing by 7, thus—