1886
THE NEW ZEALAND GAZETTE.
[No. 91]

(B.) Interfering when the Candidate selects too few Wools.

Those who evince too great slowness also require the interference of the examiner in another manner. We can lay aside here those cases in which, at the sight of the complex colours of the heap of wool, the candidate finds it difficult to select a skein resembling the sample in a collection where all the particular colours seem to differ from each other, and in consequence declares immediately that he can find none resembling the specimen. He is then told that an absolute resemblance is not demanded, and that no one asks impossibilities; that time is limited, many are waiting, &c. But there are people who—from natural slowness, from being unaccustomed to such business, from fear of making mistakes, especially if they have been previously examined and been suspected of colour-blindness, or from many other motives—proceed with the greatest caution. They do not even wish to touch the wool; or they search, select, and replace with the greatest care all the possible skeins without finding one corresponding with the sample, or that they wish to place beside it. Here, then, are two cases—on one hand, too much action with the fingers, without result; on the other, too little action. The examiner is forced to interfere in both cases.

(a.) In the case of too much manual action without corresponding practical result the examiner must be careful that the eye and hand of the candidate act simultaneously for the accomplishment of the desired end.

Some people forget that the hands should be subservient to the eye in this trial, and not act independently. Thus they are often seen to fix their eyes on one side while their hands are engaged on the other. This should be corrected, so as to save time and avoid further labour. The candidate should be told to cross his hands behind his back, to step back a pace, and quietly consider all the skeins, and, as soon as his eye has met one of those for which he is looking, to extend his hand and take it. The best plan is to advise him to look first at the sample and then at the pile, and to repeat this manœuvre until his eyes find what he is looking for.

This plan generally succeeds when nervousness from over-anxiety causes his hands to tremble; but it is not always easy to induce him to keep his hands behind his back until the moment for taking the skein in question.

(b.) In cases of great caution, the trial is hastened if the examiner come to the assistance of the candidate by holding above the pile one skein after the other, and requesting him to say whether it resembles the colour of the sample or not.

In cases where any one suspected of colour-blindness has remained some time to see the trial of others, and where, as often happens, he has remarked the skeins belonging to a required shade, he may, of course, profit by it in his own trial. But this can be prevented by shuffling the skeins.

It may be regarded as an advantage of this method that it has at command a great variety of resources. We have by no means mentioned all; and yet many who have only read this description will probably reproach us with having devoted ourselves too much to details which seem to them puerile. But we believe that those who have examined the colour-sense of a great number of persons, and acquired thereby considerable experience, will think differently.

We are convinced that time is saved by the means we have described and a more certain result obtained; whilst a practised surgeon, who has become to a certain degree a virtuoso, will accomplish his object quicker and surer by such means than one who neglects them. Recent experience fully confirms this. All those who have familiarised themselves with this method, and have had experience with colour-blindness, and of whose competence there can be no doubt, report, without exception, that it is to be fully depended on—the most practical and the best.

An advantage of the method was shown to be that those who were to be examined could be present and see each individual tested, without this interfering in the least with the certainty of the result. The individual test is even hastened thereby. The colour-blind, and even the normal-eyed who are not familiar with colours, are generally rather shy about being tested, in whatever way it is done. As the method, however, is carried out, they have more confidence. The majority are even amused. The old adage holds true here that it is easier to find fault than to do it yourself. The surgeon, who watches not only the examined, but also those around, can often see from their faces how closely the latter observe the person being tested, when he takes out the wrong colours, as also when he neglects the right ones under his eye. This gives those looking on confidence and assurance, till their turn comes, when they appear as uncertain as before they were confident. There is something attractive in the process, stimulating the interest, and not without benefit.

From this we see that our judgment of a person's colour-sense is made not only by the material result of the examination—the character of the wools selected—but often also by the way the examined acts during the test. We should mention a very common manner of persons on trial,

which, in many cases, is of great value in diagnosis. Often, in searching for the right colour, they suddenly seize a skein to lay it with the sample, but then notice it does not correspond, and put it back in the heap. This is very characteristic; and if an examiner has often seen it he can readily recognise and be assured that it is an expression of difficulty in distinguishing the differences in the colours. We frequently see this in the first test, with shades of greenish-blue and bluish-green. Here it means nothing important; but it is quite the reverse, however, when it concerns the grey or one of the confusion-colours (1-5). Uncertainty and hesitation as to these colours, which the colour-blind do not distinguish from the test-colour, even when directly comparing them, is positive proof of mistake, implying defective chromatic vision of the complete colour-blind type. No doubt the form of chromatic defect which we have called incomplete colour-blindness exists in several kinds and degrees. This is not the place to further discuss our experience on this point; and, for the practical purpose we have in view, it is not necessary. As we have explained, there are, among this class, forms of colour-blindness gradually approaching normal colour-sense. How they are distinguished has been described. We designated them as possessing feeble colour-sense.

It is, perhaps, not easy to detect these special forms by any other method, or even by our own; we therefore give the following as a means of so doing. The only way of getting at it is by determining at what distance the candidate can distinguish a small coloured surface. We have to deal, in fact, with a feeble colour-sense, which does not prevent the colours from being distinguished, but only renders it difficult. We may suppose, in comparison to the normal, that the feeble colour-sense is due either to a weaker response to the stimulation of the colour-perceptive organs of the retina, or else to a stimulation of a relatively smaller number of these organs. In either case this method would give us the same result, judging from our experience in testing the eccentric portions of the field of vision with the perimeter.

The method we here speak of shows us also the effect of habit and practice on the colour-perception, and it is worth while to dwell on this point. It not unfrequently happens that a person who by Test No. I. has been noted "incomplete colour-blind," after they know of their mistake and have practised themselves in distinguishing colours, will so comport themselves at a second trial that we have to simply mark them as of "feeble colour-sense." The same will sometimes happen with Test No. II., and it is explainable by what we have said, that between the complete lack of some one colour-sense and the incomplete there is a series of gradations, and that in such cases practice would affect the result of examinations.

All the examples given prove that many seeming trifles and plans are of value in making the examination—amongst others, the keeping the sample a little way off from the heap of worsteds, as also the removal of everything which can cause the examined doubt and uncertainty. We must not, therefore, let them do what many want to do, namely, hold a number of the worsteds in the hand at once. We must make the person being examined place each skein, as he takes it up, either with the sample or else back on the heap. Many who are not clear whether the skein is like the sample or not, instinctively put the shades most resembling the test sample at the side of the heap towards it, and thus gradually form a little bridge, but which for correctness they will not vouch for. No such half-measures must, however, be allowed.

Note C.—Colour-ignorance Test.

(1.) The object of this test is simply to ascertain whether the candidate knows the names of the three colours—red, green, and white—which it is important for every seaman to be acquainted with, and the test is to be confined to naming those colours.

(2.) One or two of the purest red and green skeins should be selected from the set of wools, and the candidate should be required to name their colours. He should also be required to name the colour of any white object, such as a piece of white paper.

(3.) If he answers correctly he should be considered to have passed the test. If he makes any mistake he should be tried with the lantern which was formerly used for colour-tests, the plain glass and the standard red and green glasses being employed for the purpose. If he does not name these glasses correctly he should be reported as having failed to pass the test.

(4.) The result of every test should be reported to the Marine Department.

All cases of failure should be reported to the Marine Department.