current passes.  Small varieties of the type-printer are employed for the distribution of news and prices in most of the large towns, being located in hotels, restaurants, saloons, and other public places, and reporting prices of stocks and bonds, horse races, and sporting and general news.  The “duplex system,” whereby two messages, one in either direction, can be sent over one wire simultaneously without interfering, and the quadruplex system, whereby four messages, two in either direction, are also sent at once, have come into use where the traffic over the lines is very great.  Both of these systems and their modifications depend on an ingenious arrangement of the apparatus at each end of the line, by which the signal currents sent out from one station do not influence the receivers there, but leave them free to indicate the currents from the distant station.  When the Wheatstone Automatic Sender is employed with these systems about 500 words per minute can be sent through the line.  Press news is generally sent by night, and it is on record, that during a great debate in Parliament, as many as half a million words poured out of the Central Telegraph Station at St. Martin’s-le-Grand in a single night to all parts of the country.

Errors occur now and then through bad penmanship or the similarity of certain signals, and amusing telegrams have been sent out, as when the nomination of Mr. Brand for the Speakership of the Commons took the form of “Proposed to brand Speaker”; and an excursion party assured their friends at home of their security by the message, “Arrived all tight.”

Telegraphs, in the literal sense of the word, which actually write the message as with a pen, and make a copy or facsimile of the original, have been invented from time to time.  Such are the “telegraphic pen” of Mr. E. A. Cowper, and the “telautographs” of Mr. J. H. Robertson and Mr. Elisha Gray.  The first two are based on a method of varying the strength of the current in accordance with the curves of the handwriting, and making the varied current actuate by means of magnetism a writing pen or stylus at the distant station.  The instrument of Gray, which is the most successful, works by intermittent currents or electrical impulses, that excite electro-magnets and move the stylus at the far end of the line.  They are too complicated for description here, and are not of much practical importance.

Telegraphs for transmitting sketches and drawings have also been devised by D’Ablincourt and others, but they have not come into general use.  Of late another step forward has been taken by Mr. Amstutz, who has invented an apparatus for transmitting photographic pictures to a distance by means of electricity.  The system may be described as a combination of the photograph and telegraph.  An ordinary negative picture is taken, and then impressed on a gelatine plate sensitised with bichromate of potash.  The parts of the gelatine in light become insoluble, while