To THE EDITOR OF THE LIFE-BOAT JOURNAL.

SIR, In the article headed ' Signals of Distress' in your last quarterly publication of August 1,1 find it stated that, in the first place," It is indispensable that signals of distress should be few in number, and readily distinguishable from all other signals." Further on, I find the statement that, in order to distinguish between sig- nals calling for a pilot, or signals of distress calling for the help of a Life-boat," no other colours would be necessary than those already required to be carried on board every ship, viz., red and green." Another paragraph states that " the bow lights, red on the port, and green on the starboard bow, which are required by law to be carried on board every English vessel, and which have been generally adopted by other nations, should not on any account be discarded in favour of uncoloured lights." The article then goes on to pro- pose " the use of the red light to summon help to save life, and the use of the green light to summon help to save property." It is then stated that " the exhibition of her red light by the NortTifleet would have at once summoned the crews of the sur- rounding anchored vessels to her rescue." The article then proposes that "every vessel should carry small red and green hand- lights, igniting by percussion, for signal purposes ;" and it ends by expressing trust " that the Board of Trade will not too hastily discard the use of colours in signals of distress." Now I quite agree with the writer of this article that the use of colours should be preserved; but I would request your permission to ventilate the question: Should those colours be red and green ? I venture to assert in reply—decidedly not! Why so ? Simply for this reason: because there are a very considerable number of persons who cannot distinguish red from green, or green from red.

To a person of ordinary vision this seems almost incredible, so unlike are these two colours to him in every respect.

It is, however, a well-known fact that there are in the world a very considerable number of colour-blind persons—so called because they confound red and green to- gether, and can never be depended upon to distinguish them.

The number of such colour-blind per- sons in the world has been estimated, by those who have gone deeply into the question, to be as high as one in fifty. So that in the channels approaching our shores, and in the estuaries of onr har- bours, as well as on the highways of mid- ocean, on board all the vessels that meet each other on opposite courses, on the darkest and thickest nights, one out of every fifty sailors, whether steering, or on the look-out, is utterly unable to distin- guish the port and starboard signals of approaching ships. How many vessels, how many crews, how many cargoes have probably been lost in consequence! May not this account for some of the numerous collisions at sea of which we read, and which seem to be almost inexplicable, unless there be some unsuspected and un- known element of uncertainty in distin- guishing the bow lights of vessels! This is a wide question. It touches not only navigation of vessels, but also railway travelling. What chance has a railway train in the hands of a guard, of an engine-driver or his mate, or of a signal- er pointsman, who is utterly unable to see the difference between a green safety light, and a red danger light by night, or be- tween the green and red arms of the signal-post by day ? I believe that, in consequence, some railway companies have already adopted blue lights and blue signals, in place of green.

The colour-blind man can distinguish blue as a safety signal, though he might not be able to say whether the danger signal were red or green. He would, how- ever, be quite sure, not being blue, that it betokened danger.

Some time ago, it was proposed to put up semaphores, with red and green arms, throughout the most crowded thorough- fares and crossings of London, to regulate the street traffic—colours perfectly undis- tinguishable to one in fifty of all the drivers of vehicles, and of all the foot passengers, who would look at them. As far as I can judge, such signals would be almost as likely to produce accidents as to prevent them.

I would therefore suggest that the use of green as a safety signal be entirely superseded, and that blue be adopted in- stead, both by land and sea; and the pro- babilities are that such a change will materially diminish accidents, many of which probably now occur in consequence of the unsuspected and undetected colour- blindness of one-fiftieth of the earth's in- habitants.

I do not write without some prac- tical knowledge of the subject, having some colour-blind ones, three out of eight children, in my own family, and being acquainted with others.

I will give two examples of this sin- gular colour-blindness in the case of one of my own sons, in order to prove the complete want of power to distinguish the two colours, red and green. On return- ing from bathing, one summer morning, my eldest son pointed to a pair of en- trance-gates, which had been newly painted a bright green, and said, " What on earth induced that man to paint his gates red ¥' On another occasion, a discussion taking place at luncheon, in reference to his colour-blindness, he got rather annoyed, and turning to a strange gentleman sitting near him, who had a reddish whisker, my son picked up a bright piece of parsley from a dish in front of him, and said triumphantly, " Your whisker is exactly the colour of this par- j sley." I could multiply such instances.

Only consider the risk of a train rushing on at the rate of 40 or 50 miles an hour, its security depending on the power of such a colour-blind person to distinguish the safety and danger sig- nals! Consider the risk of two vessels nearing each other at sea, with a helm's- man, or look-out man, utterly unable to make out which bow of the approaching vessel he was looking at—whether the light presented to his vision were red or green! All these frightful risks may be abolished by adopting blue signals and lights in place of green.

I commend this suggested change to the Lords of the Admiralty—to the Tri- nity Board, who control our lighthouses j and lightvessels—to the Board of Trade —to the Committee of the ROYAL NA- TIONAL LIFE-BOAT INSTITUTION—to the Directors and Traffic Managers of Rail- ways—and to the Authorities of the Me- tropolitan Police, who regulate the traffic of our crowded London thoroughfares.

I am, &c., Yours, I. H. G.

Honorary Secretary of a Branch of the National Life-lout Institution.

P.S.—I further recommend the con- sideration of this subject to foreigners, who, it appears from your pages, have almost unanimously adopted the red and green lights as sea signals. I ask again, How many ships, lives, and cargoes have fallen victims to this unhappy choice of colours ? It has been a case of " the blind leading the blind." [In publishing the foregoing letter, we nevertheless feel bound to say that we cannot agree with our correspondent in thinking the comparatively few excep- tional cases of colour-blindness a sufficient reason for excluding red and green signals, whether on the railway or on board ship.

The cases of colour-blindness are, we believe, much more uncommon than our correspondent supposes. "We have our- selves never met a person so affected, nor have we ever heard of accidents resulting from such a cause. It surely, therefore, would be much simpler to avoid placing such persons in situations where their defective sight might be productive of serious consequences, than to abolish a system of signals which has been found of value, and for which it might be diffi- cult to find a substitute.—ED. L. B. J.].