Human Tracks
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By GillcraftGeneral ClassificationsWe have considered the single impressions made by a human being whether barefoot or booted, and have now to consider the varieties of tracks which he may leave upon the ground. A slow-motion picture can show you the movements which a man makes in walking, and such a picture would be of the greatest use in the consideration of the scientific side of the art of tracking. The muscular motions which propel a man forward have their counterpart in the track that he leaves on the ground. I trust I may be pardoned if I make more than a passing reference to the forces which he exerts in order to make a step forward" because that is how a track is made. When a man standing desires to move forward he leans slightly forward so as to throw his centre of gravity in the direction in which he intends to go. As he does this he commences to bend the knee of the leg he intends to move forward first. To avoid complications we will assume that he intends to step off with the left leg as is usual. He bends the left knee, and, at practically the same time, in order to relieve the ankle, he raises the left heel from the ground. As the leg moves forward the whole of the sole of the foot leaves the ground, the toe being the last to lose contact. At the same time he leans slightly over to the right, throwing his weight gradually on to the right leg and foot, until they bear the full weight of his body. The right foot is flat on the ground, and the weight of the body distributed equally along the length of the sole from heel to toe. The left leg is advanced and simultaneously the centre of gravity is thrown farther forward; when there is danger of equilibrium being lost, the left leg straightens out and the left heel touches the ground. In the meantime the right leg is bent at the knee, the right heel is forced to leave the ground, with the result that the weight of the body is borne on the back of the left heel and the front of the right toe, the centre of gravity of the body being swung forward and to the left by the push of the right toe. The direction of this force causes the man to strike the ground with the outer side of the back of the heel, which goes downwards and forwards into the ground, pushing the soil, if soft, in front of it. This soil is gradually forced down and forward as the left foot comes to the ground from heel to toe. Before the right toe leaves the ground it gives a final push towards the left foot, which has the effect of pushing the soil away in a contrary direction. All the weight is then borne on the left foot and the right swings forward causing the centre of gravity again to change direction towards the right. The effect of this change of direction is to cause the left foot to exert pressure similarly. When the heel touched the ground it pushed the soil forward and slightly outwards, then it pressed it straight down as the pressure passed directly above it, and now it presses it to the rear and outwards as the left heel begins to lift for its second step. This roll of the foot is what makes the impression of the foot broader than the foot itself actually is. I have tried to make this description as short and as simple as possible: the whole action of the foot is minutely described in G. W. Gayer's Foot Prints. The reason I give it at all is that this study tells us where to look for the most marked impressions of the foot on the ground. The two most marked are those made by the outer side of the back of the heel and the inner side of the toe. The next two are those made by the ball of the foot behind the big toe and by the outer side of the foot behind the little toe. Then there is a small heap of soil thrown forward by the back edge of the heel and pressed down by the flat of the heel, and a certain amount of soil thrown back by the toe and not pressed down. Two important points arise. On hard ground there may be no other mark left on the ground except where the heel first struck the ground and where the toe last left it; the faster a man walks the more will soil be displaced by the toe, and that soil will be loose. It will be noticed that in the ordinary walk the heel meets the ground first, and similarly it will be found that in the ordinary walk the toes point slightly outward, following the direction of the thrust made by the opposite foot. I have emphasized "ordinary" because if a person is thinking about style and so on he will tend to do things that he would not ordinarily do and the track he makes will not be characteristic of him. I will try and discuss a few departures from the ordinary in the next chapter. We have now the ordinary marks left by an average man at an ordinary walk. The relationship of the left footmark to the right will vary according to the man. The distance between each footmark will be slightly over thirty inches. If a string were taken and stretched along the centre of the line of walk, it would pass over both heels, but the left toes would fall to the left of it, and the right toes to the right. If the walk were slower, more balance would be required; it is just the same on one's feet as on a bicycle, and so the heels would lie more off the centre line to the left and right respectively, the slower the walk the more would there be a tendency to place them wider apart. If the walk were faster, the heels would be more centrally planted, and there would be a tendency for the toes to point straighter forward. This question has been discussed in Stalking, but it is interesting to notice that Nature itself tends to teach us that, if we want to walk quickly, we have to point our feet straight. Mention has already been made of the tendency to push more soil back with the toe at a faster walk. In walking up a slope, the heel strikes less and less deeply as the hill gets steeper, because when the foot is brought to the ground the leg is bent at the knee. There is also a tendency to walk with the toes pointing straighter forward. In walking down a slope at an ordinary pace the feet are kept practically straight, but more flat to the ground so that the toe and the back of the heel strike less deeply than when walking on the level. In hurrying down a slope, however, the heels are stuck sharply into the ground to act as brakes, and the paces are considerably longer. We have devoted a considerable amount of space to the consideration of the track of a man walking, but the tracks left by a man at other speeds can be disposed of more speedily! When a man trots he merely speeds up his walk, so to speak, and the track he leaves is speeded up accordingly. The same characteristics in regard to the parts of the print most marked, and the soil pressed forward or back, will be present, but to a marked degree. The distance between each step will be lengthened, and as he has more balance because he is going faster, there will be a tendency for the marks to be in a straighter line. It is to be noticed that the impressions of the toes will be deeper and that of the heels correspondingly lighter, but in soft soil the marks of the heels will be easily apparent. When a man runs there is a great divergence of track according as to whether he has been trained to run fast or not. A trained runner sprinting will bring the ball of his foot only to the ground and thrust off with his toes. He leaves no mark of his heels, his paces are much longer than at a trot, and the marks left by his toes, with their marked backward push, will show in a straight line. An untrained man running fast will probably show a different kind of track altogether. It is quite possible that he will bring his heel down to the ground first in the same way as in walking only with increased force, his feet tend to point out again as in walking and the line of his track will not be so straight. This untrained man is exaggerated in what is known as "panic flight," to which even a trained runner is prone in times of danger. Invariably when the hero of a tale is flying for his life from a rogue elephant, he has never run so fast in his life before. From personal observation, and, I might add, experience, I don't believe it. In "panic flight" there is more than a tendency to forget training, with the seemingly inevitable result that the toes point out, the heels come to the ground, the line of flight is by no means straight, and the track itself shows a picture of which the painter would not be so proud if he surveyed it at his leisure afterwards. We may call the walk, the trot, and the run, the three main gaits which the human animal adopts, but for the purposes of the general classification of human tracks I propose to add three more series of tracks, those made by a man walking backwards, by a man who is carrying a burden, and by a man who is exhausted. The tracks made by men suffering from some physical infirmity or other fall more properly into some peculiar characteristics and so will be dealt with in the next chapter. In old times, according to the many stories that are handed down, thieves and other miscreants used to make a habit of walking backwards in order to throw their pursuers off the track. Possibly their pursuers were men of very small intelligence, otherwise the trick would not have come off very often. The differences between the track of a man walking forward and of a man walking backward are sufficiently striking to attract the attention of a veritable novice in the art of tracking. The movements set up by a man walking ordinarily have been fully described, and it stands to reason that if he is going to reverse the direction of these movements that the effect of them on the ground will also be reversed. This is, of course, precisely what happens. Instead of pushing off from his toe at each step he pushes off from his heel. Instead of his feet first striking the ground at the completion of each step, his toe does. The mark he makes on the ground shows then a push back from the heel and no push back from the toe. Usually, too, the steps are shorter, the line of walk is uncertain, the toes may turn in, and there may be a shuffle of the soil in a backward direction from toe to heel. Sometimes, however, in order to deceive his pursuers, a man may tie a pair of shoes on to his feet backwards. In this case the length of pace and the line of march may be more or less ordinary, but any earth thrown forward by the reversed toe will be trodden down and the earth thrown back by the reversed heel will not be pressed down. If a man is carrying a burden he has to propel himself forward and in addition the extra weight he is carrying. If the burden is very heavy his balance is affected. So we get these characteristics: the steps are shorter, the feet are planted wider apart laterally, the line of march is uncertain, and the indentations are deeper than they would ordinarily be, especially at the toe. The only real difficulty that arises is to identify the track from that of a large, heavy man, and the shorter steps and uncertainty of line are the more likely to afford the clue. If a man is exhausted, he has not the control over his legs that he ordinarily has. Anyone who has run a grueling race realizes this fact to the full. Those who haven't, have probably seen such a race run, and have noticed how the runners staggered off the track at the post. The track gives a true picture of the extent of the exhaustion. The marks left on the ground show that the feet have strayed far from a central well-balanced line, the feet are inclined to cross over each other, the line of advance is very uncertain, the outer edges of each impression are deeply indented, there is no cleanness or definite pattern in the track as a whole, it just shambles about. Some such similar track may lead to entirely different explanations than that the man was exhausted or wounded, but of that more anon. |