Now this method, though introducing a certain improvement in the system of fire signalling, is still wanting in definiteness: for it is evident that it is neither possible to anticipate, or, if you could anticipate, to write upon the rod every possible thing that may happen: and therefore, when anything unexpected in the chapter of accidents does occur, it is plainly impossible to communicate it by this method. Besides, even such statements as are written on the rods are quite indefinite; for the number of cavalry or infantry that have come, or the particular point in the territory which they have entered, the number of ships, or the amount of corn, cannot be expressed. For what cannot be known before it happens cannot have an arrangement made for expressing it. And this is the important point. For how is one to take proper measures for relief without knowing the number or direction of the enemy? Or how can the party to be relieved feel confidence or the reverse, or indeed have any conception at all of the situation, if it does not know how many ships or how much corn have been despatched by the allies? But the last method which was hit upon by Cleoxenus and Democlitus, and further elaborated by myself, is above all things definite, and made capable of indicating clearly whatever is needed at the moment; but in its working it requires attention and more than ordinarily close observation. It is as follows: Divide the alphabet into five groups of five letters each (of course the last group will be one letter short, but this will not interfere with the working of the system). The parties about to signal to each other must then prepare five tablets each, on which the several groups of letters must be written. They must then agree that the party signalling shall first raise two torches, and wait until the other raises two also. The object of this is to let each other know that they are attending. These torches having been lowered, the signalling party raises first torches on the left to indicate which of the tablets he means: for instance, one if he means the first, two if he means the second, and so on. He next raises torches on the right showing in a similar manner by their number which of the letters in the tablet he wishes to indicate to the recipient.