While these pages are passing through the press, the following particulars, apparently issued under official direction, have attracted our attention. We append them here, as they cannot fail to interest the reader:—"It appears that there are in the United Kingdom 6 miles 712 yards of pneumatic tubes in connection with the postal telegraphic system (1871). Of these, 4 miles 638 yards exist in London, and 2 miles 74 yards in the provinces—the latter being confined to Liverpool, Manchester, Birmingham, and Glasgow. Of the total length of tubes now existing, only 2 miles 1324 yards existed prior to the transfer of the telegraphs to the post office; so that no less than 3 miles 1148 yards have been laid since that date; or, in other words, the system has been considerably more than doubled in less than a year. The total length of new tubes ordered and in progress exceeds 3 miles, and when these are completed, the system will be nearly 10 miles in length. All of the tubes in the provinces, and all but two of those in London, are worked on Clark's system. The two which form an exception are those between Telegraph Street and St. Martin's-le-Grand, which are worked on Siemens' system. The former are made of lead, with a diameter varying from 1-1/4 to 2-1/4 inches—the more frequent size being 1-1/2 inches. The latter are made of iron, and have a diameter of 3 inches. The idea of iron tubes worked on Siemens' principle is derived, we believe, from Berlin, where the system is entirely of this description; and of the new tubes in progress, that from St. Martin's-le-Grand to Temple Bar will be of this kind. All of the tubes now in existence are worked in both directions by means of alternate pressure and vacuum; the motive power, in the shape of a steam-engine, being stationed at the central office, with which the out-stations have communication by this means. It is interesting to note the difference of time occupied by the different tubes in London in passing the "carriers" through from one end to the other—the speed being governed by the length and diameter of the tube, and by the circumstance whether it is carried in a straight line, or has to encounter sharp curves and bends on its way. The great advantage of this means of communication, for short distance, over the electric is, that the tubes are not liable to sudden blocks of work as the wires are, and that a dozen or more messages may be sent through, at one blow, if desired. For local telegraphs in great towns the pneumatic system is invaluable, and is certain to be greatly extended under the postal administration.

FOOTNOTES:

[D] Brian Tuke, master of the post to King Henry VIII.