A few days before this trial of the telegraph in London, Steinheil, of Munich, is said to have had one of his own invention at work there; and it is a difficult question to decide whether he or Cooke and Wheatstone were the first inventors. It is, however, a question of no consequence, as each worked independently. Since the first English electric telegraph was patented, there have been a thousand and one other contrivances of a similar kind taken out; but it may be doubted whether, for practical purposes, the original apparatus, with the improvements which its own inventors have made on it, is not still the best of them all. From being used merely to carry railway messages, the telegraph was brought into the service of the general public; the advantages of such almost instantaneous communication were readily appreciated; and eight years after Messrs. Cooke and Wheatstone took out their patent, lines of telegraph to the extent of 500 miles were in operation in England upon the original plan. In 1855 telegraphic correspondence had become so general, that the Electric Telegraph Company was started to supply the demand. In that establishment the Needle Telegraph of Wheatstone and Cooke is the one generally used, with the Chemical Recording Telegraph of Bain for special occasions. By means of the latter, blue lines of various lengths, according to an alphabet, are drawn upon a ribbon of paper, and as many as 20,000 words can be sent in an hour, though the ordinary rate is 100 per minute. In the purchase of patent rights alone, the Company have spent L170,000, and they are every year adding to the length of their wires. In June 1850 they had 6730 miles of wires, and despatched 29,245 messages a year. In December 1853 they had 24,340 miles of wires, and despatched 212,440 messages a-year. Their lines now extend over a much larger mileage, and convey a greatly increased number of messages. The Magnetic Telegraph Company have also a large extent of wires, and do a considerable business. III.--THE SUBMARINE TELEGRAPH.