criminal psychology-第67章
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enough。 The reason； then； must be different from the assigned onebut whatever it is； we need only to maintain that immediate judgment concerning numerous cases involving situations of this kind would be overhasty。 It is often said that a witness was able to see this or that under such and such illumination； or that he was unable to see it； although he denies his ability or inability。 The only solution of such contradictions is an experiment。 The attempt must be made either by the judge or some reliable third person； to discover whether； under the same conditions of illumination； anything could be seen at the place in question or not。
As to _*what_ may be seen in the distance； experiment again； is the best judge。 The human eye is so very different in each man that even the acute examination into what is known of the visual image of the Pleiades shows that the _*average_ visual capacity of classic periods is no different from our own； but still that there was great variety in visual capacity。 What enormous visual power is attributed to half…civilized and barbarous peoples； especially Indians； Esquimos； etc。！ Likewise among our own people there are hunters； mountain guides； etc。； who can see so clearly in the distance that mere stories about it might be fables。 In the Bosnian campaign of 1878 we had a soldier who in numerous cases of our great need to know the enemy's position in the distance could distinguish it with greater accuracy than we with our good field…glasses。 He was the son of a coal…miner in the Styrian mountains； and rather a fool。 Incidentally it may be added that he had an incredible； almost animal power of orientation。
As we know little concerning far…sightedness； so also we are unable to define what near…sighted people can see。 Inasmuch as their vision does not carry； they are compelled to make intellectual supplementations。 They observe the form； action； and clothes of people more accurately than sharp…eyed persons； and hence recognize acquaintances at a greater distance than the latter。 Therefore； before an assertion of a short…sighted man is doubted an experiment should be made； or at least another trustworthy short…sighted person should be asked for his opinion。
The background of objects； their movement and form have decided effects on the difference in visual perception。 It is an ancient observation that lengthy objects like poles； wires； etc。； are visible at incomparably greater distances than； e。 g。； squares of the same length。 In examination it has been shown that the boundary of accurate perception can hardly be determined。 I know a place where under favorable illumination taut； white and very thin telephone wires may be seen at a distance of more than a kilometer。 And this demands a very small angle of vision。
Humboldt calls attention to the large number of ‘‘optical fables。'' He assures us that it is certainly untrue that the stars may be seen in daylight from a deep well； from mines； or high mountains； although this has been repeatedly affirmed since Aristotle。
The explanation of our power to see very thin； long objects at a very great distance； is not our affair； but is of importance because it serves to explain a number of similar phenomena spoken of by witnesses。 We have either incorrectly to deny things we do not understand； or we have to accept a good deal that is deniable。 We will start； therefore； with the well…known fact that a point seen for a considerable time may easily disappear from perception。 This has been studied by Helmholtz and others； and he has shown how difficult it is to keep a point within the field of vision for only ten or twenty minutes。 Aubert examines older studies of the matter and concludes that this disappearance or confusion of an object is peripheral； but that fixation of a small object is always difficult。 If we fix a distant point it is disappearing at every instant so that an accurate perception is not possible； if however we fix upon a long； thin body； e。 g。； a wire； it is unnecessary to fix a single point and we may see the object with a wandering eye； hence more clearly。
Helmholtz adds that weakly objective images disappear like a wet spot on warm tin； at the moment a single point is fixed； as does e。 g。； a landscape seen at night。 This last acute observation is the basis of many a testimony concerning the sudden disappearance of an object at night。 It has helped me in many an examination； and always to advantage。
In this connection the over…estimation of the moon's illuminating power is not to be forgotten。 According to Helmholtz the power of the full moon is not more than that of a candle twelve feet away。 And how much people claim to have seen by moonlight！ Dr。 Vincent＇1＇ says that a man may be recognized during the first quarter at from two to six meters； at full moon at from seven to ten meters； and at the brightest full moon； an intimate may be recognized at from fifteen to sixteen meters。 This is approximately correct and indicates how much moonlight is over…estimated。
＇1＇ Vincent： Traitdecine lgrand du Saule。
In addition to the natural differences of sight there are also those artificially created。 How much we may help ourselves by skilful distinctions； we can recognize in the well…known and frequently… mentioned business of reading a confused handwriting。 We aim to weaken our sense…perception in favor of our imagination； i。 e。 so to reduce the clearness of the former as to be able to test upon it in some degree a larger number of images。 We hold the MS。 away from us； look at it askant； with contracted eyebrows； in different lights； and finally we read it。 Again； the converse occurs。 If we have seen something with a magnifying glass we later recognize details without its help。 Definite conditions may bring to light very great distinctions。 A body close to the face or in the middle distance looks different according as one eye or both be used in examining it。 This is an old story and explains the queer descriptions we receive of such objects as weapons and the like； which were suddenly held before the face of the deponent。 In cases of murderous assault it is certain that most uncanny stories are told； later explained by fear or total confusion or intentional dishonesty； but really to be explained by nothing more than actual optical processes。
I do not believe that binocular vision is of much importance in the law； I know of no case in ordinary vision where it matters whether one or both eyes have been used。 It is correct to assert that one side or the other of a vertically held hand will be clearer if； before looking at it with both eyes； you look at it with one or the other； but this makes little difference to our purpose。 It must be maintained that a part of what we see is seen with one eye only；if； e。 g。； I look at the sky and cover one eye with my hand； a certain portion of the heaven disappears； but I observe no alteration in the remaining portion。 When I cover the other eye； other stars disappear。 Therefore； in binocular vision certain things are seen with one eye only。 This may be of importance when an effect has been observed first with both eyes； then with one； raising the question of the difference in observationbut such a question is rare。
There are two additional things to consider。 The first is the problem of the influence of custom on increasing visual power in darkness。 This power is as a rule undervalued。 No animal； naturally； can see anything in complete darkness。 But it is almost unbelievable how much can be seen with a very little light。 Here again； prisoners tell numerous stories concerning their vision in subterranean prisons。 One saw so well as to be able to throw seven needles about the cell and then to find them again。 Another； the naturalist Quatremologie。'' Aubert tells of his having had to stay in a room so dark as to make it necessary for others to feel their way； but nevertheless being able to read books without detection because the others could not see the books。
How quickly we get used to darkness and
