Bed of nails
Encyclopedia
A bed of nails is an oblong
piece of wood
the size of a bed
with nail
s pointing upwards out of it. It appears to the spectator that anyone lying on this "bed" would be injured by the nails, but this is not so. Assuming the nails are numerous enough, the weight is distributed between them such that the pressure exerted by each nail is not enough to break the person's skin
.
One use of such a device is for magic tricks
or physics
demonstrations. A famous example requires a volunteer to lie on a bed of several thousand nails, with a board on top of him. Cinder block
s are placed on the board and then smashed with a sledgehammer
. Despite the seemingly unavoidable force, the volunteer is not harmed: the force from the blow is spread among the thousands of nails, resulting in reduced pressure; the breaking of the blocks also dissipates much of the energy from the hammer. This demonstration of the principles of weight distribution requires that the weight of the volunteer be spread over as many nails as possible. The most dangerous part is the moment of lying down or getting up, when one's weight may briefly be supported on only a few nails. Some "beds" have rails mounted at the sides to help users lie down and get up safely.
The bed of nails is used by some for meditation
, particularly in India
and other parts of Asia
.
Less traditional settings, such as science centers, may use an electronic retractable bed of nails, where the user lies on a flat plastic bed with holes in it, and can then activate the machine to have nails rise up all at once. The nails should retract before getting off the bed. This retraction eliminates the most dangerous part of a traditional bed of nails, getting on and off the bed.
Rectangle
In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles. The term "oblong" is occasionally used to refer to a non-square rectangle...
piece of wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
the size of a bed
Bed
A bed is a large piece of furniture used as a place to sleep, relax, or engage in sexual relations.Most modern beds consist of a mattress on a bed frame, with the mattress resting either on a solid base, often wooden slats, or a sprung base...
with nail
Nail (engineering)
In woodworking and construction, a nail is a pin-shaped, sharp object of hard metal or alloy used as a fastener. Formerly wrought iron, today's nails are typically made of steel, often dipped or coated to prevent corrosion in harsh conditions or improve adhesion...
s pointing upwards out of it. It appears to the spectator that anyone lying on this "bed" would be injured by the nails, but this is not so. Assuming the nails are numerous enough, the weight is distributed between them such that the pressure exerted by each nail is not enough to break the person's skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
.
One use of such a device is for magic tricks
Magic (illusion)
Magic is a performing art that entertains audiences by staging tricks or creating illusions of seemingly impossible or supernatural feats using natural means...
or physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
demonstrations. A famous example requires a volunteer to lie on a bed of several thousand nails, with a board on top of him. Cinder block
Cinder block
In the United States, a concrete masonry unit – also called concrete block, cement block, and foundation block – is a large rectangular brick used in construction. Concrete blocks are made from cast concrete, i.e. Portland cement and aggregate, usually sand and fine gravel for high-density blocks...
s are placed on the board and then smashed with a sledgehammer
Sledgehammer
A sledgehammer is a tool consisting of a large, flat head attached to a lever . The head is typically made of metal. The sledgehammer can apply more impulse than other hammers, due to its large size. Along with the mallet, it shares the ability to distribute force over a wide area...
. Despite the seemingly unavoidable force, the volunteer is not harmed: the force from the blow is spread among the thousands of nails, resulting in reduced pressure; the breaking of the blocks also dissipates much of the energy from the hammer. This demonstration of the principles of weight distribution requires that the weight of the volunteer be spread over as many nails as possible. The most dangerous part is the moment of lying down or getting up, when one's weight may briefly be supported on only a few nails. Some "beds" have rails mounted at the sides to help users lie down and get up safely.
The bed of nails is used by some for meditation
Meditation
Meditation is any form of a family of practices in which practitioners train their minds or self-induce a mode of consciousness to realize some benefit....
, particularly in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and other parts of Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
.
Less traditional settings, such as science centers, may use an electronic retractable bed of nails, where the user lies on a flat plastic bed with holes in it, and can then activate the machine to have nails rise up all at once. The nails should retract before getting off the bed. This retraction eliminates the most dangerous part of a traditional bed of nails, getting on and off the bed.