This nocturnal telegraph answered well, but was too expensive for common use.' Later on he writes to Dr.Darwin: 'I have been employed for two months in experiments upon a telegraph of my own invention.

By day, at eighteen or twenty miles distance, I show, by four pointers, isosceles triangles, twenty feet high, on four imaginary circles, eight imaginary points, which correspond with the figures 0, 1, 2, 3, 4, 5, 6, 7, so that seven thousand different combinations are formed, of four figures each, which refer to a dictionary of words.

By night, white lights are used.' Dr.Darwin in reply says: 'The telegraph you described, I dare say, would answer the purpose.

It would be like a giant wielding his long arms and talking with his fingers: and those long arms might be covered with lamps in the night.' It is curious now to read Mr.Edgeworth's words: 'I will venture to predict that it will at some future period be generally practised, not only in these islands, but that it will in time become a means of communication between the most distant parts of the world, wherever arts and sciences have civilised mankind.' It was some years later, in 1794, when Ireland was in a disturbed state, and threatened by a French invasion, that Edgeworth laid his scheme for telegraphs before the Government, and offered to keep open communication between Dublin and Cork if the Government would pay the expense.

He made a trial between two hills fifteen miles apart, and a message was sent and an answer received in five minutes.