The first modern trampoline was built by George Nissen and Larry Griswold in 1936.
Nissen was a gymnastics and diving competitor and Griswold was a
tumbler on the gymnastics team, both at the University of Iowa, United
States.
They had observed trapeze artists using a tight net to add entertainment
value to their performance and experimented by stretching a piece of
canvas, in which they had inserted grommets along each side, to an angle
iron frame by means of coiled springs. It was initially used to train
tumblers but soon became popular in its own right.
Nissen explained that the name came from the Spanish trampolín,
meaning a diving board.
Nissen had heard the word on a demonstration tour in Mexico in the late
1930s and decided to use an anglicized form as the trademark for the
apparatus.
The frame of a competitive trampoline is made of steel and can be made
to fold up for transportation to competition venues.
The trampoline bed is rectangular 4.28 by 2.14 metres (14 ft 1 in × 7 ft
0 in) in size fitted into the 5.05 by 2.91 metres (17 ft × 10 ft)
frame[8] with around 110 steel springs (the actual number may vary by
manufacturer). The bed is made of a strong fabric, although this is not
itself elastic; the elasticity is provided only by the springs. The
fabric can be woven from webbing, which is the most commonly used
material. However, in the 2007 World Championships held in Quebec City,
a Ross bed (or two-string bed), woven from individual thin strings, was
used. This type of bed gives a little extra height to the rebound.