Thus, a Queen on Q4, as shown in diagram iv, commands twenty-seven squares. Owing to the squares at her command, she is the most powerful of the Pieces, but her power would be disproportionally great were it not that she can be exchanged only for the opposing Queen without material loss. When the Queen occupies a side square, the sum of the diagonal moves possible to her is always seven.
The Bishop's Move.
The Bishop moves over any number of unoccupied squares in a diagonal line, from which it will be seen that he always occupies squares of the same color as the one on which he stands at the beginning of the game. As the King's Bishop is on a square of one color and the Queen's Bishop on a square of another color, at the opening of the game, it will be seen that the two Bishops are easily distinguished and never interfere with each other. From a center square, Q4, for example as shown on diagram v, the Bishop
