For _three_ letters, I subdivide these four Cells, by drawing an _Inner_ Square, which I assign to m, the _Outer_ Border being assigned to m'. I thus get _eight_ Cells that are needed to accommodate the eight Classes, whose peculiar Sets of Attributes are xym, xym', &c. ·---------------· | | | | ·---|---· | | | | | | |---|---|---|---| | | | | | | ·---|---· | | | | ·---------------· This last Diagram is the most complex that I use in the _Elementary_ Part of my 'Symbolic Logic.' But I may as well take this opportunity of describing the more complex ones which will appear in Part II. pg177 For _four_ letters (which I call a, b, c, d) I use this Diagram; assigning the North Half to a (and of course the _rest_ of the Diagram to a'), the West Half to b, the Horizontal Oblong to c, and the Upright Oblong to d. We have now got 16 Cells. ·---------------------· | | | | ·---|---· | | | | | | | ·---|---|---|---· | | | | | | | | |--|---|---|---|---|--| | | | | | | | | ·---|---|---|---· | | | | | | | ·---|---· | | | | ·---------------------· For _five_ letters (adding e) I subdivide the 16 Cells of the previous Diagram by _oblique_ partitions, assigning all the _upper_ portions to e, and all the _lower_ portions to e'. Here, I admit, we lose the advantage of having the e-Class all _together_, "in a ring-fence", like the other 4 Classes. Still, it is very easy to find; and the operation, of erasing it, is nearly as easy as that of erasing any other Class. We have now got 32 Cells. ·---------------------· | / | / | | / ·---|---· / | | / | / | / | / | | ·---|---|---|---· | | | / | / | / | / | | |--|---|---|---|---|--| | | / | / | / | / | | | ·---|---|---|---· | | / | / | / | / | | / ·---|---· / | | / | / | ·---------------------· For _six_ letters (adding h, as I avoid _tailed_ letters) I substitute upright crosses for the oblique partitions, assigning the 4 portions, into which each of the 16 Cells is thus divided, to the four Classes eh, eh', e'h, e'h'. We have now got 64 Cells.