Chair
A chair is a type of seat, typically designed for one person and consisting of one or more legs, a flat or slightly angled seat and a back-rest. It may be made of wood, metal, or synthetic materials, and may be padded or upholstered in various colors and fabrics.
Chairs vary in design. An armchair has armrests fixed to the seat; a recliner is upholstered and features a mechanism that lowers the chair's back and raises into place a footrest; a rocking chair has legs fixed to two long curved slats; and a wheelchair has wheels fixed to an axis under the seat.
Etymology
Chair comes from the early 13th-century English word chaere, from Old French chaiere, from Latin cathedra and ultimately Greek καθέδρα kathedra.History
The chair has been used since antiquity, although for many centuries it was a symbolic article of state and dignity rather than an article for ordinary use. "The chair" is still used as the emblem of authority in the House of Commons in the United Kingdom and Canada, and in many other settings. In keeping with this historical connotation of the "chair" as the symbol of authority, committees, boards of directors, and academic departments all have a 'chairman' or 'chair'. Endowed professorships are referred to as chairs.It was not until the 16th century that chairs became common. Until then, people sat on chests, benches, and stools, which were the ordinary seats of everyday life. The number of chairs which have survived from an earlier date is exceedingly limited; most examples are of ecclesiastical, seigneurial or feudal origin.
Chairs have existed since at least the Early Dynastic Period of Egypt. They were covered with cloth or leather, were made of carved wood, and were much lower than today's chairs – chair seats were sometimes only high. In ancient Egypt, chairs appear to have been of great richness and splendor. Fashioned of ebony and ivory, or of carved and gilded wood, they were covered with costly materials, magnificent patterns and supported upon representations of the legs of beasts or the figures of captives. Generally speaking, the higher ranked an individual was, the taller and more sumptuous was the chair he sat on and the greater the honor. On state occasions, the pharaoh sat on a throne, often with a little footstool in front of it.
The average Egyptian family seldom had chairs, and if they did, it was usually only the master of the household who sat on a chair. Among the better off, the chairs might be painted to look like the ornate inlaid and carved chairs of the rich, but the craftsmanship was usually poor.
The earliest images of chairs in China are from 6th-century Buddhist murals and stele, but the practice of sitting in chairs at that time was rare. It was not until the 12th century that chairs became widespread in China. Scholars disagree on the reasons for the adoption of the chair. The most common theories are that the chair was an outgrowth of indigenous Chinese furniture, that it evolved from a camp stool imported from Central Asia, that it was introduced to China by Christian missionaries in the 7th century, and that the chair came to China from India as a form of Buddhist monastic furniture. In modern China, unlike Korea or Japan, it is no longer common to sit at floor level.
In Europe, it was owing in great measure to the Renaissance that the chair ceased to be a privilege of state and became a standard item of furniture for anyone who could afford to buy it. Once the idea of privilege faded the chair speedily came into general use. Almost at once the chair began to change every few years to reflect the fashions of the day.
Thomas Edward Bowdich visited the main Palace of the Ashanti Empire in 1819, and observed chairs engrossed with gold in the empire.
In the 1800s, chairs became more common in American households and usually there was a chair provided for every family member to sit down to dinner. By the 1830s, factory-manufactured “fancy chairs” like those by Sears, Roebuck, and Co. allowed families to purchase machined sets. With the Industrial Revolution, chairs became much more available.
The 20th century saw an increasing use of technology in chair construction with such things as all-metal folding chairs, metal-legged chairs, the Slumber Chair, moulded plastic chairs and ergonomic chairs. The recliner became a popular form, at least in part due to radio and television. In the 1930s, stair lifts were commercially available to help people suffering from Polio and other diseases to navigate stairs.
The modern movement of the 1960s produced new forms of chairs: the butterfly chair, bean bags, and the egg-shaped pod chair that turns. It also introduced the first mass-produced plastic chairs such as the Bofinger chair in 1966. Technological advances led to molded plywood and wood laminate chairs, as well as chairs made of leather or polymers. Mechanical technology incorporated into the chair enabled adjustable chairs, especially for office use. Motors embedded in the chair resulted in massage chairs.
Materials
Chairs can be made from wood, metal, or other strong materials, like stone or acrylic. In some cases, multiple materials are used to construct a chair; for example, the legs and frame may be made from metal and the seat and back may be made from plastic. Chairs may have hard surfaces of wood, metal, plastic, or other materials, or some or all of these hard surfaces may be covered with upholstery or padding. The design may be made of porous materials, or be drilled with holes for decoration; a low back or gaps can provide ventilation. The back may extend above the height of the occupant's head, which can optionally contain a headrest. Chairs can also be made from more creative materials, such as recycled materials like cutlery and wooden play bricks, pencils, plumbing tubes, rope, corrugated cardboard, and PVC pipe.In rare cases, chairs are made out of unusual materials, especially as a form of art or experimentation. Raimonds Cirulis, a Latvian interior designer, created a volcanic hanging chair that is handmade out of volcanic rock. Peter Brenner, a Dutch-born German designer, has created a chair made from lollipop sugar – of confectioners' sugar.
Design and ergonomics
Chair design considers intended usage, ergonomics, as well as non-ergonomic functional requirements such as size, stacking ability, folding ability, weight, durability, stain resistance, and artistic design.Seat height
Ergonomic design distributes the weight of the occupant to various parts of the body. This is done by having an easily adjustable seat height. A seat that is higher results in dangling feet and increased pressure on the underside of the knees. It may also result in no weight on the feet which means more weight elsewhere. A lower seat may shift too much weight to the "seat bones". Gas springs are attached to the body of the chair in order to give height adjustment and more comfort to the user.Some chairs have foot rests. Around 15% of women and 2% of men need foot rests, even at the chair height. A stool or other simple chair may have a simple straight or curved bar near the bottom for the sitter to place their feet on.
Actual chair dimensions are determined by measurements of the human body or anthropometric measurements. The two most relevant anthropometric measurements for chair design are the popliteal height and buttock popliteal length.
For someone seated, the popliteal height is the distance from the underside of the foot to the underside of the thigh at the knees. It is sometimes called the "stool height". The term "sitting height" is reserved for the height to the top of the head when seated. For American men, the median popliteal height is and for American women it is. The popliteal height, after adjusting for heels, clothing and other issues, is used to determine the height of the chair seat. Mass-produced chairs are typically high.
Researchers such as Mary Blade and Galen Cranz found that sitting on the edge of a high stool with feet on the floor is less harmful for the lower back than sitting up straight on a conventional chair.
Reclining angle
Different types of chairs can have a variety of seating positions, depending on the intended task. Typically, chairs intended for people completing work or dining can only recline very slightly. Dental chairs are necessarily reclined. Research has shown that the best seated posture is a reclined posture of 100°–110°. In order to recline, the back-rest may be independently adjustable. A reclining seat and back will reduce the load on the occupant's back muscles. In general, if the occupant is supposed to sit for a long time, weight needs to be taken off the seat area and thus "easy" chairs intended for long periods of sitting are generally at least slightly reclined.Back and head support
The back of the chair will support some of the weight of the occupant, reducing the weight on other parts of the body. Some back-rests support only the lumbar region, while shoulder height back-rests support the entire back and shoulders. Headrests support the head as well and are important in vehicles for preventing "whiplash" neck injuries in rear-end collisions where the head is jerked back suddenly. Reclining chairs typically have at least shoulder-height back-rests to shift weight to the shoulders.Padding
There may be cases where padding is not desirable, such as chairs that are intended primarily for outdoor use. Where padding is not desirable, contouring may be used instead. A contoured seat pan attempts to distribute weight without padding. By matching the shape of the occupant's buttocks, weight is distributed and maximum pressure is reduced.Armrests
A chair may or may not have armrests; chairs with armrests are termed "armchairs". In French, a distinction is made between fauteuil and chaise, the terms for chairs with and without armrests, respectively. In Germany, an armchair was once called a Krankensessel, or sick-chair, because it was intended for people who were too ill to stand or sit without extra support.If present, armrests will support part of the body weight through the arms if the arms are resting on the armrests. Elbow rest height is used to determine the height of the armrests. Armrests should support the forearm and not the sensitive elbow area. Hence in some chair designs, the armrest is not continuous to the chair back, but is missing in the elbow area. Armrests further have the function of making entry and exit from the chair easier.