In making the drawing from which a chair is to be constructed care must be taken to determine whether it is to have castors or not. If it is to have them the leg must be shortened accordingly, for the average castor is one and five eighths inches high from the floor to the top of the plate screwed to the under side of the chair leg.

The depth of the seat, that is, the distance from the front to the back, is varied with the height. It is not entirely a matter of appearance, though within limits it may be made to please the eye. Generally, the lower the seat, the deeper it should be. If the chair seat is high, and too deep, the feet of the occupant will not rest on the floor, if he sits back in the chair. Such a chair is uncomfortable, and any one using it either sits on the front edge, perhaps tilting the chair forward on the front legs, or uses a foot stool. Either there is no support for the back or none for the feet when such a chair is used.

A chair that is too low, and shallow in the seat, obliges the occupant to stretch his legs out in front or he becomes cramped against Ihe back of the chair so that almost unconsciously he tips it backwards. Many have tried to devise a rule by which the correct proportion between height and depth of seat can be determined, but thus far none seems to suit all conditions. Approximately, the sum of the depth of the seat plus its height is equal to thirty-five inches.

Chairs for use at a table may be from fifteen to eighteen inches deep, comfortable, upholstered chairs, twenty inches deep; large, low, upholstered chairs may be twenty-four inches deep inside measurement. The width of the seat, from side to side, may be any size called for by the character of the design, except in the case of an arm chair, when it must not be too narrow.

Arm chairs are necessarily wider than others, in order that there may be room between the arms for a person to sit easily without feeling crowded. The space between the arms should not be less than twenty inches at the front edge of the seat, nor less than eighteen at the back. The arm ought also to be of such a height, slope, and length that it will form a convenient rest for the hand and forearm, as well as a side support for the body. Here again arises the conditions of the use of the chair; for, if it is to be used at a table the arm ought not to project forward in a way to prevent placing the chair as close to the table as desirable for comfort. For such chairs the arm post, that is the upright from the seat supporting the arm, if a continuation of the front leg, is curved backward sufficiently to keep the scroll of the arm back of, or on a line with, the front edge of the chair seat.

The arm post may, however, not be a part of the front post, but entirely independent. Then, it also recedes that the scroll of the arm may be kept well away from the front of the chair. Plate VIII. This arrangement has the advantage of leaving the front of the seat free from obstructions that too closely confine the sitter.

Arm posts on the front edge of the seat interfere with ladies' dresses, and in many of the French chairs the arm posts not only recede, but curve outward at the same time, thus giving considerable more freedom for the person and the clothing.

It is customary to make the width of the seat at the back a trifle less than at the front, in order to avoid the optical illusion of its appearing wider at the back than at the front, as is sometimes the case when the sides are parallel. This difference in width is about two or three inches.

Hepplewhite gives as the general dimensions of a chair: width in front 20 inches, depth of seat 17 inches, height of seat frame 17 inches (his chair seats are about 1-2 or 1 inch above the frame) ; total height 3 feet 1 inch. The height of a chair back is a matter of design, and it may be proportioned accordingly. It may, or may not, be inclined to the seat; its side posts may be slightly inclined, while the middle slopes considerably, thus providing a hollow in which the shoulders of the sitter rest comfortably. Modern chairs usually have the back inclined, though chairs for use in the entrance hall and dining-room are, perhaps, made with the back vertical.

The amount of slope given the back depends on the use to which the chair is put. An easy chair reclines the most, and just as a low chair is deeper in the seat than a high chair, so, too, may the back slope more on a low seat chair than on a high one. A chair with arms may also have a back more inclined than one without.

The appearance of stability is largely influenced by the inclination of the back. So much so, that it is found desirable in most chairs to slope the back legs outwards a little to counteract the apparent tendency of the chair to upset. An arbitrary rule is: the slope of the back for a chair without arms should not be more than one-fourth the depth of the seat and chairs with arms not more than one half.

The legs and rails of chairs should appear firm enough to support, not alone the chair, but the person that sits in it. For chairs with straight legs, whether turned or square in section, the matter of strength is one of size only. The bandy-leg, however, requires more care that the curve may not be too great. Rococo work defies the laws of wood structure, yet it may be properly made so as, in a measure, to reconcile the critic to its eccentricity. In describing the rococo table leg (page 14) it was told how to overcome the apparent, as well as actual, weakness of this form of support, and what was said then will apply as well to chair legs.

Many chairs are more or less upholstered. It may be the seat only that is thus treated, or the entire woodwork, except perhaps the legs, may be hidden by a covering of upholsterer's work.

The simplest methods of upholstering seats are the two padded varieties in which no springs are used. No.1, Plate XL, shows a cheap way when a hard seat is not objectionable, and it is desirable that there should be a little elasticity. In the illustration the padding is fastened directly to the frame of the seat so when complete it appears the same as an upholstered, spring seat. In some instances the padding is fastened to a separate, loose frame resting in a rebate of the seat frame, and if the chair is turned bottom up the seat will fall out. Such is the way Chippendale and Hepplewhite chairs are often made.