+-------------------------------------------------------+ | | +---+---+--+--+--+--+--+--+---+---+--+--+---+---+---+---+ | A | A | | | | | | |*a*|*a*| | |*a*|*a*|*a*|*a*| +---+---+--+--+--+--+--+--+---+---+--+--+---+---+---+---+ | | +---+---+--+--+--+--+--+--+---+---+--+--+---+---+---+---+ | B | B | | | | | | | B | B | | |*b*|*b*|*b*|*b*| +---+---+--+--+--+--+--+--+---+---+--+--+---+---+---+---+ | | +---+---+--+--+--+--+--+--+---+---+--+--+---+---+---+---+ | C | C | | | | | | | C | C | | | C | C |*c*|*c*| +---+---+--+--+--+--+--+--+---+---+--+--+---+---+---+---+ | | +---+---+--+--+--+--+--+--+---+---+--+--+---+---+---+---+ | D |*d*| | | | | | | D |*d*| | | D |*d*| D |*d*| +---+---+--+--+--+--+--+--+---+---+--+--+---+---+---+---+ | | +-------------------------------------------------------+ The operator will readily collect the various conclusions in the manner described in previous pages, as, for instance that A is always C, that not-C is not-B and not-A; and not-B is not-A but either C or not-C. The results are thus to be read off exactly as in the case of the Logical Slate, or the Logical Abacus. Disjunctive propositions are to be treated in an exactly similar manner. Thus, to work the premises A = AB ꖌ AC B ꖌ C = BD ꖌ CD, it is only necessary to press in succession the keys A (left), copula, A (right), B, ꖌ, A, C, full stop. B (left), ꖌ, C, copula, B (right), D, ꖌ, C, D, full stop. The combinations then remaining will be as follows ABCD *a*BCD *abc*D AB*c*D *a*B*c*D *abcd.* A*c*CD *ab*CD On pressing the left-hand key A, all the possible combinations which do not contain A will disappear, and the description of A may be gathered from what remain, namely that it is always D. The full-stop key restores all combinations consistent with the premises and any other selection may be made, as say not-D, which will be found to be always not-A, not-B, and not-C.