In this paper the author described his method of constructing crystal models of paper or cardboard by means of plaiting. In the ordinary crystal "nets" (such as, according to Mr. Gotham, were constructed by himself and shown at the Royal Society as early as 1847) the faces of the model are drawn in juxtaposition on cardboard and cut out, some of the lines being only partially cut through ; the net is then folded up so as to form a solid figure, and the faces are united at their edges by gum.

In the models described and exhibited by Mr. Gotham, the faces are so drawn as to be disposed along strips; these strips are united to each other at one end, and can then be folded together by a process resembling plaiting, in which the strips pass alternately under and over each other.