### David Singmaster's demonstration of his hinged model of
Henry Perigal's dissection, which appears in

Dissections: Plane & Fancy,
by Greg N. Frederickson:

At IPP19 in August 1999,
David Singmaster mentioned to me that about ten years earlier he had had
a hinged model constructed
of Henry Perigal's dissection of two squares to one.
Since I was very interested, David, who lives in London,
brought the model to the meeting the next day.
The pictures show him sitting in the lobby of the hotel
and demonstrating his model.

. . .

Whereas I would prefer to leave the small square separate,
David had had all five pieces hinged together,
as shown on the left above.
The picture on the right shows the five pieces folded around
so that they form the two small squares sitting side by side.
David had also had a right triangle constructed whose sides are the
sidelengths of the three squares,
and he had placed this triangle on top of the medium size square.
Interestingly, the ratio of sidelengths appears to be
more or less the same as what is
in the diagram on the south front of
Henry Perigal's monument
in the churchyard at Wennington.

Back to the photo gallery
for *Dissections: Plane & Fancy*.

*Copyright 1999, Greg N. Frederickson*.

Permission is granted to any purchaser of
*Dissections: Plane & Fancy*
to print out a copy
of this page for his or her own personal use.

*Last updated September 7, 1999.*