Placing it in his own instrument, it at once reproduces itself exactly in his autograph, and with every peculiarity, blot, or erasure, at the nearest office. Here the copy is placed in the proper box, and at once reproduced in the office nearest the residence of the person to whom it is addressed, and forwarded in the same manner to him. A letter, therefore, covering one of these slips, and saying as much as we could write in an average hand upon a large sheet of letter-paper, is delivered within five minutes at most from the time of despatch, no matter how great the distance. I remarked that this method of communication made privacy impossible. "But," replied the official, "how could we possibly have time to indulge in curiosity? We have to sort hundreds of these papers in an hour. We have just time to look at the address, place them in the proper box, and touch the spring which sets the electric current at work. If secrecy were needed a cipher would easily secure it, for you will observe that by this telegraph whatever is inscribed on the sheet is mechanically reproduced; and it would be as easy to send a picture as a message." I learnt that a post of marvellous perfection had, some thousand years ago, delivered letters all over Mars, but it was now employed only for the delivery of parcels. Perhaps half the commerce of Mars, except that in metals and agricultural produce, depends on this post. Purchasers of standard articles describe by the telegraph-letter to a tradesman the exact amount and pattern of the goods required, and these are despatched at once; a system of banking, very completely organised, enabling the buyer to pay at once by a telegraphic order.