This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
To make a comfortable chair some respect must be paid to the measurements of the human body in a sitting posture. Thus in a man 5 ft. 9 in. high, the distance from heel to beneath knee-joint will bo 18 in.; from knee-joint to bottom of back, 21 in.; from bottom of back to shoulder-blades, 22-23 in.; thence to back of poll 6-7 in. These indicate the dimensions desirable in the legs, seat, and back of the chair, the legs being somewhat shortened in the case of easy chairs.
Fig. 689 well illustrates the construction of a strong comfortable dining-room chair. The requisite suitable wood having been procured it is dealt with as follows : - Having first of all got out the back and 2 back feet, mortise and tenon them, putting them together loose. This will give the pitch or angle of the complete back, and allow of "fits" being made for the top and splat; then mortise and tenon both the latter again, lit up the -whole of the back loose, and if the joints are close and satisfactory, nothing now prevents the glueing up of this part of the chair. The nest portion to proceed with is the front; either mark off the front rail with a square and straight-edge, or make a fit, which is more convenient. The square end or templet shown can then be used for mortising and tenoning the front, and the front end of side rails. It will be noticed that the back tenons are not square; they "spring in" slightly towards the chair. This is necessary in such a shaped seat for ease in cramping, because if made square, when the chair was cramped up the tenons would break up. It is only in marking these tenons that the angle end of the templet proves useful, the square end being used for all the other joints in the chair.
The close braces shown in the chawing are merely fitted and screwed into position. They are introduced more for the sake of appearance than for utility, for a well-made chair should not need such aids to strength. In this shape of chair, mortising and tenoning are secured throughout, whilst a comfortable line adapted to the body is also obtained. This is one advantage of having the back feet to " run out," or go to the top of the chair, because it makes the mortising of the top possible, whereas in put-on tops recourse must be had to dowels, which are always more or less unreliable. The importance of well-seasoned wood need scarcely be urged; more especially let the wood be dry upon which the tenons are made, for this reason, if the mortised wood should be a little fresh it will shrink to the former, and thus make the tenons hold the tighter.
Fig. 690 represents a show-wood gentlemen's easy chair, whose construction may be summarized as follows: - Having cut all the wood to the required dimensions, proceed to mortise and tenon the back feet, top, and splat to the back, putting them together loose to test the fitting. When the back is built up, get out the beech rails and lay the moulding slips; make the mortices and tenons and put in the side rails, front and cross-frame seat to the back. Shape the arms to sleeve-board pattern, wider in front than at back. Glue and screw the moulding piece underneath them; and then loosely mortise and tenon the small end of the arm into the back, doing the same with the turned stump, which latter should be lapped over the side rail of the seat to give perfect strength, as if only dowelled or mortised on the top it is apt to get loose. The under bracket may next be marked off and shaped, then secured to both back and arm, and all glucd up completely. Rebate pieces are screwed in at the sides of the back, but are not needed at the top and splat, as sufficient wood remains for the upholsterer to tack to.
In this class of chair it is difficult to secure perfect head rest without carrying the back so high as to let the stuffing come under the poll; but a stuff over back may be made by putting beech rails into the back and having the rise flat on top.
Fig. 691 shows a ladies' easy chair to match the last mentioned, and made in the same way, the dimensions and design only differing. Some makers are in favour of dowelling rather than mortising and tenoning, as taking away less wood; but unless the dowels are dry, the fitting is perfect, and the glue is good, "rickets" will soon follow. A simple protection for a dowel joint is to plaster a piece of strong canvas over. Still dowels may give way, while a tenon with a pin through it cannot.
In the divan chair illustrated in Fig. 692, the frame is set out to allow for what is known as double stuffing, or spring edges to seat. The making of such a frame is a simple matter, and may be briefly described as follows: - First make a mould for the back, taking care that it is a nice graceful line; no other mould will be required for the job, as the rest of the pieces are perfectly straight. Get out stuff to the thickness indicated, and then fit up the back, square the top and bottom, as shown; leave 4 1/2 in. between the top of the seat and the stuffing rail to allow for the double stuffing mentioned above. If the chair is to be upholstered in the ordinary way, with the usual thickness of rolls, only 2 in. need be allowed between these rails. Having thus got the back up, glue and frame up the front, and then cross-frame the chair together from back to front. In fitting the spindle stump which supports the arm, the best plan is to first fit the arm on the stump, a pin having been left on the latter, which may be allowed to come right through the arm, and can thus be wedged in the top when finally fixed.
Before fixing, however, mortise and lap over the square lower portion of the stump on to the side rails; when properly adjusted, the arms can be glued up, and the chair frame is complete. It is as well to place an iron batten under the seat to give extra strength. An excellent plan to finish off a frame of this kind is to glue over the joints a strong piece of canvas; thus protected, the "rickets" are almost impossible, even if the stuff is a little "fresh." Either dowels, or mortising and tenoning, may be employed in the manufacture. The sizes given will answer equally well for a similar chair with "stuffed-in" arms. If, however, the latter are required to be full in the stuffing, an extra 2 in. should be allowed in width of seat. For a ladies' chair to go with this, the same moulds and proportions will do, if made 2 in. less all ways (except in height of legs, which may be about the same). As a rule, ladies' chairs are better without arms, in consequence of the extensive character of the dresses sometimes adopted. Arms are possible and comforting, if made 12 or 14 in. long, to catch the elbows.