Artistic Anatomy of Animals

Finally, very frequently to O, H, from the internal angle of the eye to the insertion of the throat into the maxillary trough (G. and B.).

An equality still more frequent is that which exists between the distances:

O, B, from the internal angle of the eye to the margin of the lips;

A, H, from the nape to the insertion of the throat into the maxillary trough;

And H, B, from this latter point to the margins of the lips.

The Head, Front View (Fig. 110).—If, to continue our examination, adds M. Duhousset, we regard the head from the front, we find its greatest width at A, B, the extreme points of the orbital arches.

This width is 22 centimetres.

It is again equal to:

A, C, from one arch to the nape;

A, D, from one arch to the middle of the face.

D, E, from the middle of the face to the margin of the lips.

From the auditory canal, G, to the maxillary spine, F, is the same distance as from this point to the margins of the lips, E, or, better, to the end of the teeth.

The line G, C, from the auditory meatus to the nape, is equal to the sixth of the head, 10 centimetres; the line A, G, from the orbital arch to the auditory meatus, is a little longer, and measures 12 centimetres.

The distance F, I, comprised between the maxillary spines, is 18 centimetres.

It is equal to:

O, O, the distance between the internal angles of the eyes (G. and B.);

F, R, the distance from the maxillary spine to the superior commissure of the corresponding nostril (G. and. B.);

F, P, from the maxillary spine to the salt-cellar.[66]

From the nape to the internal angle of the eye, C, O, is the same distance as from this latter point to the commissure of the lips, O, T; and from the maxillary spine to the upper lip F, S (G. and B.).

The distance apart, T, T, of the two commissures of the lips gives, very nearly, the distance from the superior border of the orbital arch to the base of the ear or the auditory meatus. In the state of rest, the outer limit of the separation of the nostrils does not exceed the width of the knee;[67] we frequently find the same distance intercepted above the nape by the tranquil ears. In the figure (Fig. 110) we have intentionally represented them directed in a different plane, in order to show that when the pinna is turned backward, it none the less preserves the contour of bracket form, more or less pronounced according to the breeding of the subject, and characterizing in repose the interior curves of the ear.

The extreme limit of the lips, M, N, but very slightly exceeds that of the nostrils; on many heads of harmonious proportions this distance is found to be the half of A, B.

In order not to interrupt the course of the preceding exposition, we decided to withhold till afterwards some reflections which have been suggested to us by certain of the proportions which are there indicated. The proportions in question are important—we may even say that they are fundamental, for they have for object the relation which exists between the length of the head, the height of the body, and the length of the latter.

We have already seen that, according to Bourgelat, the length of the head is contained two and a half times in the length of the body, from the point of the arm to the point of the buttock; and, also, two and a half times in the height measured from the apex of the withers to the ground (see p. 265). We saw afterwards that M. Duhousset, having adopted these proportions, pointed out, further, that the same dimension was again found equally to exist from the summit of the crupper to the ground—a height which Bourgelat considered as being of less extent. There results, then, from the latter proportions, which we have just recalled, this interesting fact: that they simplify very much, from the point of view of design, the placing in position of the horse, on the condition always that this latter be always viewed directly on one of its lateral aspects.

Indeed, in this case, if we except the neck and the head, the body, inasmuch as its height and its length are equal, may be inscribed in a square, of which one of the sides corresponds to the withers and to the summit of the crupper, two of the other sides to the point of the arm and to that of the buttock the fourth being represented by the ground. This is simple, but this simplicity even has its inconveniences.

It follows that this proportion, thus expressed, seems to exclude from every artistic representation certain categories of horses, which upon the whole might be regarded as beautiful, and the existence of which in any case it would be a pity not to indicate.

Without attaining exactly to three times the length of the head, as some authors (Saint-Bel, Vallon) have announced, the body of the horse, nevertheless, measured as is stated above, frequently contains it more than two and a half times. We give in support of this some outline reproductions, executed after photographs (Figs. 112, 113, 114).

There still remains the question regarding the equality of the height and of the length of the body of the horse.

This equality, after the proportions previously indicated, would seem bound to appear in all the cases observed. Now, if we measure the examples reproduced in Figs. 112, 113, and 114, we shall see that sometimes the two dimensions are unequal, the height being greater than the length, or inversely.

It is the same, if we examine a certain number of specimens; we are able to determine that the proportion chosen in preference by authors is not exactly that which is oftenest met with. It will, very probably, be objected that it is so for the most beautiful types, and that the indifferent ones are generally the more numerous. The essential thing would be to know, above all, if the type of two heads and a half of length and of height is really the only beautiful one. However that may be, of the fifty African horses measured by M. Duhousset, only fourteen possessed the equality indicated; twenty-six were less long than high, and ten more long than high.[68]

CHAPTER V

THE PACES OF THE HORSE

As a completion of the studies we have just been making, some notions relative to the paces of the horse seem to us to be absolutely indicated.

Let it be permitted to us to remind the reader in this connection that we have already been for twenty-one years occupied with this question, and that by means of an articulated figure, a sort of movable mannikin, we have endeavoured to demonstrate to artists the differences which characterize the various paces of the horse.[69] The arrangement then employed cannot, evidently, be used in the present volume, but we will inspire ourselves, in the preparation of the present chapter, with the elements of demonstration which we have employed, and which, in the course of our teaching, we have had the satisfaction of seeing favourably received.

The progressive movements by which an individual transports himself from one place to another do not operate according to a unique method and with a constantly uniform velocity. These various modes of progression are designated under the name of paces.

It is extremely difficult to analyze, by simple observation, the movements which characterize these gaits. Let us, for example, examine the displacements made by the limbs of a horse during that of walking; if we have no notion of these displacements, it will be, so to speak, impossible to determine in what order they are executed. The sight of the imprints left on the ground by the hoofs is not a sufficient means of demonstration, especially for artists. The noise made by the blows of these limbs, or by the little bells of different timbre suspended from them, are absolutely in the same case.

Processes enabling us to fix or to register the paces are in every way preferable. Such really exist; they are: instantaneous photography and those which constitute the graphic method of Professor Marey. The results given by the photograph are certainly appreciable; but, from the didactic point of view, we give the preference to the graphic method, the general characters and the mode of application of which we now proceed to analyze.[70]

It is necessary to understand first of all, in this connection, that which relates to a man’s walking pace.

The method of Professor Marey rests on the following principle: Suppose two rubber globes connected with one another by a tube. If we compress one of these globes, the air which it contains will be driven into the other, and will afterwards return when the pressure has ceased. Nothing more simple, evidently; but it is necessary to describe it in detail in order the better to comprehend that which follows: The walker who is the subject of experiment is furnished with special shoes (Fig. 115), having thick indiarubber soles, hollowed in the interior, so that the whole thus constituted forms a sort of hollow cushion which is compressed under the influence of the pressure of the foot on the ground. A tube which is attached to a registering apparatus, which the person who is walking carries in his hand, communicates with this cavity (Fig. 116). This apparatus is formed of a metal drum, which is closed at its upper part by a flexible membrane. Each time that one of the man’s feet presses on the ground, the air contained in the cavity of the sole of the shoe is driven into the drum, which we have just mentioned, and the flexible membrane of this drum is elevated. To this membrane is attached a vertical rod which supports a horizontal style.

The tracings thus obtained, which are read from left to right, are sufficiently simple; but to understand them properly, it is necessary to remember that the style undergoes a movement of ascensional displacement during each pressure of a foot, and that, on the other hand, it descends when the latter is separated from the ground. We also see, on the tracing which it leaves, a line which ascends and then descends; the meaning of this is that first the foot presses on the ground, and is afterwards raised from it.

On the tracing (Fig. 117), the line D relates to the right foot; the line G, which is dotted so that it may not be confused with the preceding, corresponds to the left foot. The line G first ascends; the meaning of which is that the left foot presses on the ground; afterwards it descends: this indicates that the pressure of the foot has ceased. It is the same for the right foot. As we see, the pressures succeed each other; when the left foot touches the ground, the right is separated from it; when the latter presses the ground, it is the left which no longer rests there.

The line O is related to the movements of the body, as indicated by the oscillations of the head. We will neglect these.

But this tracing, which serves us for an example, is not, it must indeed be said, of very easy reading; it would be still less so if the paces of a horse were registered, for there would then be four lines, the entanglement of which would cause greater complication.

These difficulties of reading need be no longer feared, if we transform the tracing into a notation by means of the following diagram.

There are drawn (Fig. 118) below the graphic tracing two horizontal lines (1, 2). From the point where the line D rises (commencement of the pressure of the right foot), and from the point where this same line descends (end of the same pressure), we let fall two vertical lines joining the two horizontal ones mentioned above. At this plane, and between the two vertical lines, we mark a broad white one (a, b). This expresses, by its length, the duration of the period of pressure of the right foot. In doing the same for the line G, we obtain for the indication of a pressure of the left foot an interval of the same kind, in which are marked cross-lines, or which is tinted gray, in order to avoid all confusion with the preceding tracing.

This notation can, with sufficient exactitude, be compared to that which is employed in the musical scale. The horizontal lines 1 and 2 represent the compass. We there also see notes; these are the bars indicating the pressure, of which the value—that is to say, the duration—is represented by the length of these bars. It is the same with regard to the intervals of silence: these are expressed by the intervals which separate the pressures, and correspond to the moments in which, during certain paces, such as running, the body is raised from the ground. Besides, we see intervals of this kind on the notation reproduced (Fig. 118) relative to the running of man.

In order to make the signification of these tracings still better understood, we reproduce four varieties of them (Fig. 119).

The first notation is that of ordinary walking. The pressures succeed each other regularly.

The second shows what takes place during the ascent of a staircase. At a certain moment, the weight of the body is upon both feet at the same time, one of them not quitting the lower step, until the other is already in contact with the step above. Accordingly, there is thus produced an overriding of the pressures.

The third is relative to running, and has already been represented in Fig. 118. The pressures of the feet are separated by the times of suspension.

The fourth also represents running, but in this case more rapid and characterized by the shorter pressures, the slightly longer periods of suspension intervals, and the quicker succession of movements.

Before putting aside the indications relating to the walking movements of man—indications which it was necessary to give in order to render intelligible those which are connected with the paces of the horse—we have yet to fix the value of that which we call ‘a step.’

It is generally admitted that a step is constituted by the series of movements which are produced between the corresponding phases of the action of one foot and that of the other—for example, between the moment at which the right foot commences its pressure on the ground and that at which the left foot commences its own. It is necessary to adopt here another method of looking at it, and to regard the preceding as being but a half-step. The step should then be defined as being constituted by the series of movements which are executed between two similar positions of the same foot—as, for example, between the commencement of a pressure of the right foot and the similar phase of the following pressure of the same foot. We shall soon understand the importance of this definition.

Before entering on the details of the paces of the horse, it is necessary to see how the limbs of the latter oscillate during the period of a complete step; or, which is the same thing, to determine what the displacements are which a limb executes between two similar positions of its foot.

If we examine one of the limbs during a forward movement of the animal, we see that this limb passes through two principal phases: (1) It is raised from the ground; (2) it resumes contact with the ground. Each of these phases is divided into three periods of time, which we proceed to analyze in connection with the anterior limb.

The foot quits the ground (Fig. 120, C); this may be called lifting; the limb is oblique in direction downwards and backwards. This same limb is flexed and carried forward (Fig. 120, B), and, as it is supported by the action of its flexors, this is the period named suspension; the hoof is vertical. Then the limb is carried still further forward, becoming extended (Fig. 120, A); the heel is lowered, and the foot, being oblique, is directed towards the ground; this is the placing.

Then takes place pressure (Fig. 121). The foot has just been placed on the ground; the limb is oblique in direction downwards and forwards; this we call commencement of the pressure (Fig. 121, A). Then the body, being carried forward, whilst the hoof, D, is fixed on the ground, the limb becomes vertical: this stage is mid-pressure (Fig. 121, B). Finally, the progression of the body continuing, the limb becomes oblique downwards and backwards; it is now at the termination of pressure (Fig. 121, C), and proceeds to lift itself anew if another step is to be made.

In conclusion, the inferior extremity of the limb describes, from its elevation to its being placed on the ground, an arc of a circle around its superior extremity (Fig. 121, D); whilst, during the pressure, it is its superior extremity which describes one around its inferior extremity, then fixed on the ground (Fig. 121, D).

If we simultaneously examine the two fore-limbs, we remark that when one of them begins its pressure the other ends it, and vice versâ.

As to the hind-limbs, the oscillations are similar to those of the fore ones. In the second half of the pressure—that is, when they are passing from the vertical direction (Fig. 122, A) to extreme obliquity backwards (Fig. 122, C)—the effect of their action is to give propulsion to the body.

The fore and hind limbs make the same number of steps, and the steps have the same length.

The limbs of any quadruped—but we make special allusion to those of the horse—are divided into groups in the following manner:

The anterior pair constitutes the anterior biped. The posterior biped is that formed by the posterior limbs.

The name of lateral biped serves to designate the whole formed by the two limbs of the same side. The right fore-limb and the right hind-limb form the right lateral biped. The two others form the left lateral biped.

A fore-limb and hind-limb belonging to the opposite side form a diagonal biped, which also takes the name of the fore-limb which forms a part of it. Thus, the right diagonal biped is formed by the association of the right fore-limb and the left hind one. The left diagonal biped is, consequently, the inverse.

It is necessary to remember well these preliminary indications; it is the only means of comprehending with facility that which is about to follow.

Let us first return to the grouping of the limbs. The denominations anterior and posterior bipeds render clearly perceptible the comparison which consists in regarding a horse when walking as capable of being represented by two men marching one behind the other, and making the same number of steps. According as they move the legs of the same side at the same time in ‘covering the step,’ or march in contretemps step, we find reproduced all the rhythms which characterize the different paces of the horse.

Professor Marey has studied these paces by a similar method to that which he adopted for the walking of man, and which we have already described. He employed hollow balls fixed under the hoofs, and a registering apparatus with four styles, each corresponding to one of the limbs. The tracing obtained is rather complicated, since two sets of lines are found marked. But a notation similar to that of which we have spoken can be discovered, and its exact signification should now be determined. For this purpose, we have selected the most simple (see Fig. 123). We there see, placed in two superimposed lines, the pressure markings of the right feet (white bands), and of the left feet (gray bands). On the upper line are found those related to the fore-legs; the lower lines contain those associated with the hind-legs. It is, in brief, the superposition of two notations of the human walking movements. And seeing that, as we have previously pointed out, we may make a comparison between a quadruped and two men placed one behind the other, it is easy to understand the significance of the superimposed notations, if we accustom ourselves to look on them as the notations of two bipeds.

To read these notations—that is, to learn to know what occurs at each of the movements of the pace—it is necessary, indeed, to remember that they should be examined in vertical sections; it is to each of these sections—of these vertical divisions—that each of the movements which we more particularly wish to analyze corresponds.

We proceed to study first the pace of ambling, because it is the most simple; we shall then consider the trot, and, finally, we shall examine that which is the most complicated, viz., the step.

The Amble.—To give an exact idea of the general character of the amble, let us fancy the two men whom we discussed above marching one behind the other and walking in step—that is, moving the legs of the same side simultaneously. They will thus represent the amble, which, indeed, results from the alternate displacements of the lateral bipeds; the limbs of the same side (right or left) execute the same movements in the same time.

This is what the notation indicates (Fig. 123). We there see that the pressures of the right fore-foot, marked by the white bands in the upper range, are exactly superposed on those of the right hind one, which are marked by a similar band on the lower line; this means that the pressures took place in the same time. We there see also a similar arrangement of the gray bands, which has a similar significance for the left fore and hind feet.

And if we recollect the three phases of pressure (see p. 289, and Figs. 121, 122), we shall comprehend, in looking at the diagrams, that, at the initial stage (A), the limbs are commencing their pressure, and are oblique downwards and forwards; that afterwards (B) the two limbs are vertical, since they are at the middle of the pressure stage; and that finally (C) they are oblique downwards and backwards, for it is then the termination of their pressure (Fig. 124).

During the time that the right limbs are pressing (notation, white bands) the left limbs are raised; afterwards these latter take up the pressure (gray bands), and then the right limbs are raised in their turn.

During the pace of ambling the weight of the body, which is wholly sustained by the limbs of one side only, is not in equilibrium, so that the limbs which are raised return by a brisk movement to the position of support in order to re-establish it.

The Trot.—We have just seen that, in order to represent the amble, the two marchers moved their right limbs simultaneously, and then their left ones.

Let us suppose now that the hinder man anticipated by half a pace the movement of the front one, then will be found realized the association and the nature of the displacements of the limbs during the pace of the trot.

By this anticipation of a half-step (we have defined, p. 288, what is to be understood by the word step), it follows that when the marcher who is in front advances his right leg it is the left leg of the marcher who follows him that is carried in the same direction. We should thus conclude from this that the trot is characterized by a succession of displacements of the diagonal bipeds.

Indeed, if we examine the notation of this gait (Fig. 125), we see that with the pressure of the right fore-foot is found associated the pressure of the left hind-foot. It is, accordingly, a typical diagonal biped (Fig. 126).

But it is necessary to add that these groups of pressures do not succeed one another without interruption, except in the slow trot. In the ordinary trot, or in that in which the animal’s strides are very long, the body between each of the double pressures which we have just been considering is projected forward with such force that it remains for an instant separated from the ground. This is what we designate by the name of time of suspension (Fig. 127). The notation in this case would be slightly different from that which we reproduce above, in this sense: that between the diagonal pressures there then would be found an interval, since during the time the body is suspended none of the feet can produce a pressure-mark (see, with regard to these intervals, the notations of the running of a man, Fig. 118, and Fig. 119, 3, 4).

The Walk.—Although slow, a feature which would seem to make it possible to permit its analysis in a horse when walking, this pace is difficult to comprehend without sufficient preliminary study.

We saw above that in order to represent the amble the marchers had to move the legs of the same side simultaneously. We have also just seen that in order to represent the trot the marcher at the back had to anticipate by a half-step. Suppose, now, that this same marcher anticipates the man in front by a quarter-step only, or by a half-pressure period, and thus will be found realized the order of succession of the limbs in the gait or pace called the walk. The feet meet the ground one after the other, since they are each in advance by half the duration of a pressure. The strokes are four in number during the period of a step of this pace; in the amble and in the trot they do not exceed two, for then the limbs strike the ground in lateral diagonal pairs.

If we examine the notation of the pace of walking (Fig. 128), we see that the right fore-foot commences its pressure when the right hind-foot is in the middle of its own, and that the hinder left begins in the middle of that of the right fore-foot, and that it is itself at the midst of its pressure when the left fore-foot touches the ground, etc. In a word, the foot-fallings occur in the following order and at regular intervals—the fore right foot is here considered as acting first: right fore, left hind, left fore, right hind, and so on in succession.

As to the nature of the bipeds which succeed one another, it is easy to understand them by means of the notation. In reading this from left to right, we see that the associations of pressure are first made by the two right feet, then by a right foot and a left one, then by two left feet, and, finally, by a left and right. It is, accordingly, a succession this time of lateral and diagonal pressures.