THE PHONOMETER.

Globe, Volume IV, Issue 398, 21 September 1875, Page 3

THE PHONOMETER.

... : .» —. —_ \_From the Times;'] One of the most fruitful sources of collision in navigation is foggy weather ; a murky atmosphere is of ten the cause of far greater anxiety to the mariner than are reefs, icebergs, and many -other dangers of the deep, The present system of fog-signalling at sea removes those in command of ships but one degree from the utter state of helplessness in which its introduction found them. It consists simply in one ship announcing to another, by steam whistle, fog horn, or other means, that .she is somewhere in her vicinity, but as to what her.course is nothing can possibly be known, so that each can only slacken her speed and steer iman imaginary right course, which has but too often proved a really wrong one. Nor are the perplexities of the position diminished, but sadly increased, by the unseen presence of a third or even a fourth vessel, and it will never be known how many ships have gone .down with all hands during fogs. Survivors there are now and then to tell of these disasters, but they are few and far between, and it is not too much to assume that of our niissi jg ships a very large number have been' cut down in a fog. The anxious experiences of Captain R. E. Harris, during many dense fogs, led him to attempt the solution of the problem of comparative safety for vessels under such conditions. He knew that at night, in clear weather, his ship's course was made known to others, and the courses of others to him,- by visible means, and it occurred to him that he might so improve the audible means he had at command for rendering the presence of his ship known in a fog as to make her course known also. This idea he has worked out to a practical end, embodying it in an instrument to which he has given the name of phonometer, By means of this invention the officer in command .of a steamer can make known in which quadrant of the compass his vessel is steering, navigation being thus greatly facilitated, and the risk or' accident reduced to a minimum, either in narrow waters, or in the open sea. The apparatus consists of the mechanism of a clock placed in a horizontal position under a special dial. The seconds are arranged near the outer circumference of the dial, which is about Bin in diameter, while the Hour and minute dial is about 2in in diameter, and is placed on the lower part where the seconds dial of a watch is usually sunk. There are four seconds hands placed at right angles to each other and radiating from the centre of the main dial. Outside the seconds circles are marked five black segments with intervals between them. One segment measures ten seconds in length, and the other ;four five seconds each, with intervals of three seconds. Outside the glass which protects the dial and pivotted at its centre is a brass segment plate so arranged as to obscure those segments on the dial not required for immediate use, and thus to prevent error in signalling. Around the dial and outside it is a flat ring of metal about 2in broad on which all the points of the compass are marked. The apparatus is placed on a stand with the upper part of the dial towards the head of the ship, the stand being fixed on the bridge just by the steamwhistle so that both are under the direct control of the officer in command. In using the phonometer the compass ring, or dumb-card, as Captain Harris terms it, which is a very important feature of the instrument, is moved round until the true point on which the ship is sailing is in a line with the ship's head, all the true points of the horizon being thus indicated. These points being accurately known, it follows that all steamers in each other's vicinity fitted with the phonometer will have the true quadrants of the compass distinctly and eoncordantly represented. The steam-whistle or fog-horn is the important adjunct of the phonometer, aud it is the duration of each whistle or blast and their number that indicates the course of the ship. The black segment covering 10 seconds of space is a measure of 10 seconds of time, the other segmenjß, indicating periods of different 'dura'tion, and. a whistle of 10 seconds' duration indicates that the vessel is steering within the quadrant from N.'to "E, £ N] '■ 'Assuming this to, be the course of the vessel, the brass-covering segment would exclude all the other black segments, and the officer would wait until one of the four second hands entered that segment. He would, start the whistle ai}d .hold it on during the time-the hand traversed "that rsegment,.and shut off steam the moment , the hand reached the end of that segment. This operation must be repeated at intervals

during the contiuuance of the fog. Another ship coming within sound would at once know the course of the first, and would indicate her track in like manner. Following out Captain Harris's code, two blasts, each of five seconds' duration, with an interval of three seconds, represents from E. to S. ■]■ E. Three blasts of similar duration and interval represents from S. to W. ;',- S., while four blasts of the same length and spaces indicates from W. to N. \ W. The special object of the four seconds hands is to enable the operator to reply readily to the signals from other ships, which could not be done if the revolution of. a single hand had to be waited for* By the peculiar construction of the dial the necessity of counting the seconds when signalling is entirely obviated. The apparatus having been designed by a sailor, and being based upon nautical data, commends itself at once to the nautical mind, presenting no new theory, but being engrafted on ordinary practice. An inspection of its working has led us to the conclusion that, subject to such slight codal modifications as practice might suggest, it presents the true solution of the problem of safe navigation in foggy weather.