View source for Biscornu

{{refimprove|date=December 2009}}
[[File:Thai biscornu with orchid cross-stitch decoration.jpg|thumb|A [[Thailand|Thai]]-themed biscornu, stitched on 14-count white Aida.]]
A '''biscornu''' is a small, octagonal, stuffed ornamental [[pincushion]].<ref>{{Cite journal |last=Saluja |first=Kavita |date=2017 |title="The Rabbit Hole" – New Frameworks of Awareness for Fashion Pedagogy |url=https://thescopes.org/journal/art-and-design/art-and-design-15/the-rabbit-hole-new-frameworks-of-awareness-for-fashion-pedagogy |journal=Scope (Art & Design) |volume=15 |pages=120–127}}</ref>  It is usually made out of [[Aida cloth]] or [[linen]],<ref name="Watts">{{cite book|last=Watts|first=Bobbie|title=Teach Yourself to Make Biscornu (Leisure Arts #5406)|url=https://books.google.com/books?id=U4N3CDORQZUC|accessdate=9 August 2014|date=January 2012|publisher=Leisure Arts|isbn=978-1-60900-122-3|page=1}}</ref>  sewn from two square sheets of cloth (forming the top and bottom of the cushion) in such a way that each corner of one square is hemmed to the middle of a side of the opposite square.<ref>{{cite web|url=http://www.nordicneedle.net/guides/how-to-make-biscornu/|title=Biscornu How To|work=Nordic Needle|accessdate=2017-11-30}}</ref><ref name=":0">{{Cite journal |last=Seaton |first=Katherine A. |date=2021-10-02 |title=Textile D-forms and D 4d |journal=Journal of Mathematics and the Arts |language=en |volume=15 |issue=3–4 |pages=207–217 |doi=10.1080/17513472.2021.1991134 |s2cid=232257692 |issn=1751-3472|doi-access=free }}</ref>
[[Embroidery]], [[Hardanger embroidery|hardanger]], and/or [[cross-stitch]] are used to decorate the top and bottom of the cushion.  A [[button]] is typically secured in the center of the cushion to give a small depression on the top.<ref>{{Cite web |last= |date=2017-04-27 |title=Biscornu |url=https://www.trc-leiden.nl/trc-needles/individual-textiles-and-textile-types/accessories/biscornu |access-date=2022-10-19 |website=TRC Needles |publisher=Textile Research Center Leiden |language=en-gb}}</ref>  [[Bead]]s, [[tassel]]s and other objects can decorate the biscornu.<ref name="Watts" />  They are typically able to fit in the palm of your hand.  The name is derived from the [[French language|French]] adjective, ''[[wikt:biscornu|biscornu]]'', meaning skewed, quirky or irregular.
Mathematically, two squares joined together in the pattern of a biscornu will form the boundary of a unique [[convex polyhedron]], by [[Alexandrov's uniqueness theorem]].<ref name=":0" /><ref>{{cite book
| last1 = Devadoss | first1 = Satyan L. | author1-link = Satyan Devadoss
| last2 = O'Rourke | first2 = Joseph | author2-link = Joseph O'Rourke (professor)
| isbn = 978-0-691-14553-2
| mr = 2790764
| pages = 185
| publisher = Princeton University Press | location = Princeton, NJ
| title = Discrete and Computational Geometry
| url = https://books.google.com/books?id=InJL6iAaIQQC&pg=PA185
| year = 2011}}.</ref> In the case of a biscornu, this polyhedron is a flattened [[square antiprism]], with ten faces: two smaller squares (diagonally inset into the squares from which the shape is formed) and eight [[isosceles right triangle]]s (the corners of its original squares) around the sides. However an actual biscornu will have a somewhat more rounded shape than this polyhedron.
==See also==
*[[Paper bag problem]], on the shape of a pillow formed by hemming two squares together corner-to-corner and edge-to-edge
==References==
{{Reflist}}
[[Category:Embroidery]]
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