Models of the French telegraph have been so often exhibited, and the machine itself is so well known, that it is not necessary to describe it minutely in this place. It is sufficient to say that it consists of a tall pole, with three movable arms, which may be seen at a considerable distance through telescopes; these arms may be set in as many different positions as are requisite to express all the different letters of the alphabet. By a successive combination of letters shown in this manner, words and sentences are formed and intelligence communicated. No doubt can be made of the utility of this machine, as it has been applied to the most important purposes. It is obviously liable to mistakes, from the number of changes requisite for each word, and from the velocity with which it must be moved to convey intelligence with any tolerable expedition. The name, however, which is well chosen, has become so familiar, that I shall, with a slight alteration, adopt it for the apparatus which I am going to describe. _Telegraph_ is a proper name for a machine which describes at a distance. _Telelograph_, or contractedly _Tellograph_, is a proper name for a machine that describes _words_ at a distance. Dr. Hooke, to whom every mechanic philosopher must recur, has written an essay upon the subject of conveying swift intelligence, in which he proposes to use large wooden letters in succession. The siege of Vienna turned his attention to the business. His method is more cumbrous than the French telegraph, but far less liable to error. I tried it before I had seen Hooke's work, in the year 1767 in London, and I could distinctly read letters illuminated with lamps in Hampstead Churchyard, from the house of Mr. Elers in Great Russell Street, Bloomsbury, to whom I refer for date and circumstance. To him and to Mr. E. Delaval, F.R.S., to Mr. Perrot, of Hare Hatch, and to Mr Woulfe the chemist, I refer for the precedency which I claim in this invention. In that year I invented the idea of my present tellograph, proposing to make use of windmill sails instead of the hands or pointers which I now employ. Mr. Perrot was so good as to accompany me more than once to a hill near his house to observe with a telescope the windmill at Nettlebed, which places are, I think, sixteen miles asunder. My intention at that time was to convey not only a swift but an unsuspected mode of intelligence. By means of common windmills this might have been effected, before an account of the French telegraph was made public. My machinery consists of four triangular pointers or hands [each upon a separate pedestal, ranged along in a row], each of which points like the hand of a clock to different situations in the circles which they describe. It is easy to distinguish whether a hand moving vertically points perpendicularly downwards or upwards, horizontally to the right or left, or to any of the four intermediate positions.