Burr puzzles are interlocking puzzles known in Europe and Asia since at least the 18th century. Traditionally they are made from wood, but some modern versions use plastic (for reasons of economy) while those of collector's quality may be made from brass. The wooden burr puzzles are usually precision-made for tight fit and require special wood so that the pieces do not change shape too much in changing temperature and humidity.
The most common type of six-piece burr was invented by O.W.Brown in 1916.
The burr puzzle gets its name from the most traditional shape for the finished puzzle, a symmetrical arrangement of intersecting cuboids thought to resemble a seed burr, but similar puzzles can have other forms: a ball, a human figure, a ship, a bird or a star-like shape.
The mathematical properties of burr puzzles have been studied by Bill Cutler.
Famous quotes containing the words burr and/or puzzle:
“Heaven sometimes hedges a rare character about with ungainliness and odium, as the burr that protects the fruit.”
—Ralph Waldo Emerson (1803–1882)
“What are you now? If we could touch one another,
if these our separate entities could come to grips,
clenched like a Chinese puzzle . . . yesterday
I stood in a crowded street that was live with people,
and no one spoke a word, and the morning shone.
Everyone silent, moving. . . . Take my hand. Speak to me.”
—Muriel Rukeyser (1913–1980)