What the carrier-pigeon was in the conveyance of intelligence in the middle ages, and even within a few years, the electric telegraph is in the present day. The carrier-pigeon went out from a besieged castle, to ask for succour, in eastern countries, five centuries ago. The electric telegraph, land and submarine, brings the tidings of slaughter and sickness from Sebastopol, and England and France send instant reinforcements. The carrier-pigeon, in the last century, was despatched by the merchants of the English factory, from Scanderoon to Aleppo, to announce the arrival of the company's ships. The electric telegraph communicates to London the arrival of an Australian packet at Southampton. Within the last ten years one of the annual expenses of a London newspaper was 1800_l._ for pigeon expresses. The pigeons have lost their employment. The price of stocks and shares in 'Change-alley is known every quarter of an hour upon the exchanges of our great commercial marts; and the closing price of the French funds is in type before midnight at our daily newspaper-offices. The carrier-pigeon travelled sixty miles an hour. The time which it takes to transmit a message by the electric telegraph is inappreciable. The newspapers of the United States employ the electric telegraph far more extensively than our English papers; for the distances between one State and one city and another State and another city are so great, that steam travelling would not accomplish the object of communication with sufficient rapidity. The density of our population renders the employment of the telegraph less necessary for the ordinary transmission of intelligence. But private curiosity, in a time of great public interest, steps in; and one of the most remarkable exhibitions of our provincial towns at the time at which we are writing--when an agonizing anxiety for the fortunes of our heroic defenders in the Black Sea is the chief thought of millions--is the crowd about the telegraph-office to know something more than the morning paper, brought by railway speed, can furnish to this universal excitement. In America the distance between Quebec and New Orleans, a distance of three thousand miles, is overleaped by the electric telegraph. Two lines, each two thousand miles long, connect New York with New Orleans; and over this space messages are transmitted, and answers received, in three hours. When we read long paragraphs in the London morning papers, received by electric telegraph after midnight from Paris, we wonder how this is accomplished. Eighteen words, which are equal to about two newspaper lines, are transmitted every minute; and the full message from Dover, carefully transcribed, is in the hands of the newspaper editor in half an hour.