| COLOR OF THE SQUARE | WHITE BACKGROUND | BLACK |
| White | 39´´ | |
| Red | 1´ 43´´ | 59´´ |
| Light Green | 1´ 54´´ | 1´ 49´´ |
| Dirty Red | 3´ 27´´ | 1´ 23´´ |
| Blue | 5´ 43´´ | 4´ 17´´ |
| Brown | 4´ 55´´ | 1´ 23´´ |
| Light Blue | 2´ 17´´ | 1´ 23´´ |
| Orange | 1´ 8´´ | 0´ 39´´ |
| Gray | 4´ 17´´ | 1´ 23´´ |
| Rose | 2´ 18´´ | 3´ 49´´ |
| Yellow | 3´ 27´´ | 0´ 39´´ |
It is interesting to notice that the angle for blue on a white background is almost nine times that for white, orange, or yellow on a black background. In cases where colors are of importance, therefore, it will be necessary to discover the color and the nature of its background before the accuracy of the witness can be established.
3. It is well known that in the diminution of brightnesses red disappears before blue, and that at night, when all colors have disappeared, the blue of heaven is still visible. So if anybody asserts that he has been able to see the blue of a man’s coat but not his red-brown trousers, his statement is possibly true, while the converse would be untrue. But there are no reliable or consonant accounts of the order in which colors disappear in increasing darkness. The knowledge of this order would help a great deal in the administration of criminal justice.
4. The retina will not see red at the periphery, because there are no red rods there. A stick of red sealing wax drawn across the eye from right to left, appears at the periphery of the visual field to be black. If, then, a witness has not looked right at a definitely red object, and has seen it askance, he has certainly not observed its color. The experiment may be made by anybody.
5. According to Quantz[181] objects in less refractable colors (red, orange, yellow, and purple) look 0.2 to 3.6% bigger against white, while blue, blue-green, and violet objects appear from 0.2 to 2.2% smaller. Dark and long-lined objects seem longer; bright and horizontal seem wider. And these facts are significant when witnesses judge of size.
6. If colors are observed through small openings, especially through very small holes, the nuances become essentially different and green may even seem colorless.
7. According to Aubert, sparkle consists of the fact that one point in a body is very bright while the brightness diminishes almost absolutely from that point; e.g., a glancing wire has a very narrow bright line with deep shadows on each side; a ball of mercury in a thermometer, a shining point and then deep shadow. When we see this we say it sparkles because we unite it with a number of similar observations. It is therefore conceivable that at a great distance, under conditions of sharp or accidental illuminations, etc., we are likely to see things as sparkling which do not do so in the least. With the concept “sparkling,” moreover, we tend to unite, at least under certain circumstances, definite images, and hence “glancing weapons” are often seen in places where there were only quite harmless dull objects. So also coins are seen to sparkle where really there are none.
Section 39. (3) The Blind Spot.
Everybody knows what the blind spot is, and every psychology and physiology text-book talks about it. But as a rule it is identified only with the little point and the tiny cross pictured in the text-books, and it is supposed that it does not much matter if the little cross, under certain circumstances, can not be seen. But it must not be forgotten that the size of the blind spot increases with the distance so that at a fairly great distance, possibly half the length of a room, the blind spot becomes so great that a man’s head may disappear from the field of vision. According to Helmholtz: “The effect of the blind spot is very significant. If we make a little cross on a piece of paper and then a spot the size of a pea two inches to the right, and if we look at the cross with the left eye closed, the spot disappears. The size of the blind spot is large enough to cover in the heavens a plate which has twelve times the diameter of the moon. It may cover a human face at a distance of 6´, but we do not observe this because we generally fill out the void. If we see a line in the place in question, we see it unbroken, because we know it to be so, and therefore supply the missing part.”