must move.

body be placed slantingly in a strong current, and the hands made to grasp a stone or branch. In this case the body is raised to the surface of the stream by the action of the running water, the body remaining motionless. The quantity of water which, under the circumstances, impinges against the body in a given time is much greater than if the body was simply immersed in still water. To increase the area of support, either the supporting medium or the body supported The body is supported in water very much as the kite is supported in air. In both cases the body and the kite are made to strike the water and the air at a slight upward angle. When the extremities are made to move in a horizontal or slightly downward direction, they at once propel and support the body. When, however, they are made to act in an upward direction, as in diving, they submerge the body. This shows that the movements of the swimming surfaces may, according to their direction, either augment or destroy buoyancy. The swimming surfaces enable the seal, sea-bear, otter, ornithorhynchus, bird, etc., to disappear from and regain the surface of the water. Similar remarks may be made of the whale, dugong, manatee, and fish.

Man, in order to swim, must learn the art of swimming. He must serve a longer or shorter apprenticeship to a new form of locomotion, and acquire a new order of movements. It is otherwise with the majority of animals. Almost all quadrupeds can swim the first time they are immersed, as may readily be ascertained by throwing a newly born kitten or puppy into the water. The same may be said of the greater number of birds. This is accounted for by the fact that quadrupeds and birds are lighter, bulk for bulk, than water, but more especially, because in walking and running the movements made by their extremities are precisely those required in swimming. They have nothing to learn, as it were. They are buoyant naturally, and if they move their limbs at all, which they do instinctively, they swim of necessity. It is different with man. The movements made by him in walking and running are not those made by him in swimming; neither is the position resorted to in swimming that which characterizes him on land. The vertical position

is not adapted for water, and, as a consequence, he requires to abandon it and assume a horizontal one; he requires, in fact, to throw himself flat upon the water, either upon his side, or upon his dorsal or ventral aspect. This position assimilates him to the quadruped and bird, the fish, and everything that swims; the trunks of all swimming animals being placed in a prone position. Whenever the horizontal position is assumed, the swimmer can advance in any direction he pleases. His extremities are quite free, and only require to be moved in definite directions to produce definite results. The body can be propelled by the two arms, or the two legs; or by the right arm and leg, or the left arm and leg; or by the right arm and left leg, or the left arm and right leg. Most progress is made when the two arms and the two legs are employed. An expert swimmer can do whatever he chooses in water. Thus he can throw himself upon his back, and by extending his arms obliquely above his head until they are in the same plane with his body, can float without any exertion whatever; or, maintaining the floating position, he can fold his arms upon his chest and by alternately flexing and extending his lower extremities, can propel himself with ease and at considerable speed; or, keeping his legs in the extended position and motionless, he can propel himself by keeping his arms close to his body, and causing his hands to work like sculls, so as to make figure-of-8 loops in the water. This motion greatly resembles that made by the swimming wings of the penguin. It is most effective when the hands are turned slightly upwards, and a greater or less backward thrust given each time the hands reciprocate. The progress made at first is slow, but latterly very rapid, the rapidity increasing according to the momentum acquired. The swimmer, in addition to the foregoing methods, can throw himself upon his face, and by alternately flexing and extending his arms and legs, can float and propel himself for long periods with perfect safety and with comparatively little exertion. He can also assume the vertical position, and by remaining perfectly motionless, or by treading the water with his feet, can prevent himself from sinking; nay more, he can turn a somersault in the water either in a forward or backward

direction. The position most commonly assumed in swimming is the prone one, where the ventral surface of the body is directed towards the water. In this case the anterior and posterior extremities are simultaneously flexed and drawn towards the body slowly, after which they are simultaneously and rapidly extended. The swimming of the frog conveys an idea of the movement.1 In ordinary swimming, when the anterior and posterior extremities are simultaneously flexed, and afterwards simultaneously extended, the hands and feet describe four ellipses; an arrangement which, as explained, increases the area of support furnished by the moving parts. The ellipses are shown at fig. 38; the continuous lines representing extension, the dotted lines flexion.

Thus when the arms and legs are pushed away from the body, the arms describe the inner sides of the ellipses (fig. 38, a a), the legs describing the outer sides (cc). When the arms and legs are drawn towards the body, the arms describe the outer sides of the ellipses (bb), the legs describing the inner sides (dd). As the body advances, the ellipses are opened out and loops formed, as at e e, f f of fig. 39. If the speed attained is sufficiently high, the loops are converted into

1 The frog in swimming leisurely frequently causes its extremities to move diagonally and alternately. When, however, pursued and alarmed, it folds its fore legs, and causes its hind ones to move simultaneously and with great vigour by a series of sudden jerks, similar to those made by man when swimming on his back.

F

waved lines, as in walking and flying.-(Vide gg, h h of fig. 40, p. 81, and compare with fig. 18, p. 37, and figs. 71 and 73, p. 144.) The swimming of man, like the walking, swimming, and flying of animals, is effected by alternately flexing and extending the limbs, as shown more particularly at fig. 41, A, B, C.

A

B

C

FIG. 41.-A shows the arms and legs folded or flexed and drawn towards the mesial line of the body.-Original.

B shows the arms and legs opened out or extended and carried away from the mesial line of the body.-Original.

C shows the arms and legs in an intermediate position, i.e. when they are neither flexed nor extended. The arms and legs require to be in the position shown at A before they can assume that represented at B, and they require to be in the position shown at B before they can assume that represented at C. When the arms and legs are successively assuming the positions indicated at A, B, and C, they move in ellipses, as explained.Original.

By alternately flexing and extending the limbs, the angles made by their several parts with each other are decreased and increased,—an arrangement which diminishes and augments the degree of resistance experienced by the swimming surfaces, which by this means are made to elude and seize the water by turns. This result is further secured by the limbs being made to move more slowly in flexion than in extension, and by the limbs being made to rotate in the direction of their length in such a manner as to diminish the resistance experienced during the former movement, and increase it during the latter. When the arms are extended, the palms of the hands and the inner surfaces of the arms are directed downwards, and assist in buoying up the anterior portion of the body. The hands are screwed slightly round towards the end of extension, the palms acting

in an outward and backward direction (fig. 41, B). In this movement the posterior surfaces of the arms take part; the palms and posterior portions of the arms contributing to the propulsion of the body. When the arms are flexed, the flat of the hands is directed downwards (fig. 41, C). Towards the end of flexion the hands are slightly depressed, which has the effect of forcing the body upwards, and hence the bobbing or vertical wave-movement observed in the majority of swimmers.1

During flexion the posterior surfaces of the arms act powerfully as propellers, from the fact of their striking the water obliquely in a backward direction. I avoid the terms back and forward strokes, because the arms and hands, so long as they move, support and propel. There is no period either in extension or flexion in which they are not effective. When the legs are pushed away from the body, or extended (a movement which is effected rapidly and with great energy, as shown at fig. 41, B), the soles of the feet, the anterior surfaces of the legs, and the posterior surfaces of the thighs, are directed outwards and backwards. This enables them to seize the water with great avidity, and to propel the body forward. The efficiency of the legs and feet as propelling organs during extension is increased by their becoming more or less straight, and by their being moved with greater rapidity than in flexion; there being a general back-thrust of the limbs as a whole, and a particular back-thrust of their several parts.2 In this movement the inner surfaces of the legs and thighs act as sustaining organs and assist in floating the posterior part of the body. The slightly inclined position. of the body in the water, and the forward motion acquired in swimming, contribute to this result. When the legs and feet are drawn towards the body or flexed, as seen at fig. 41, C, A, 1 The professional swimmer avoids bobbing, and rests the side of his head on the water to diminish its weight and increase speed.

2 The greater power possessed by the limbs during extension, and more especially towards the end of extension, is well illustrated by the kick of the horse; the hind feet dealing a terrible blow when they have reached their maximum distance from the body. Ostlers are well aware of this fact, and in grooming a horse keep always very close to his hind quarters, so that if he does throw up they are forced back but not injured.