rather than on either side of it. The extremities are consequently employed in the best manner possible for developing their power and reducing the friction to forward motion caused by their action. This arrangement greatly increases the length of the effective stroke, both of the arms and legs, this being equal to nearly half an ellipse. Thus when the left arm and leg are thrust forward, the arm describes the curve a b (fig. 42), the leg e describing a similar curve. As the right side of the body virtually recedes when the left side advances, the right arm describes the curve c d, while the left arm is describing the curve a b; the right leg f describing a curve the opposite of that described by e (compare arrows).

The advancing of the right and left sides of

a

FIG. 42. Overhand Swimming.-Original.

the body alternately, in a nearly straight line, greatly con tributes to continuity of motion, the impulse being applied now to the right side and now to the left, and the limbs being disposed and worked in such a manner as in a great measure to reduce friction and prevent dead points or halts. When the left arm and leg are being thrust forward (a b, e of fig. 42), the right arm and leg strike very nearly directly backward (c d, f of fig. 42). The right arm and leg, and the resistance which they experience from the water consequently form a point d'appui for the left arm and leg; the two sides of the body twisting and screwing upon a moveable fulcrum (the water). -an arrangement which secures a maximum of propulsion with a minimum of resistance and a minimum of slip. The propulsive power is increased by the concave surfaces of the hands and feet being directed backwards during the back stroke, and by the arms being made to throw their back water in a slightly outward direction, so as not to impede the advance of the legs. The overhand method of swimming

is the most expeditious yet discovered, but it is fatiguing, and can only be indulged in for short distances.

An improvement on the foregoing for long distances is that known as the side stroke. In this method, as the term indicates, the body is thrown more decidedly upon the side. Either side may be employed, some preferring to swim on the right side, and some on the left; others swimming alternately on the right and left sides. In swimming by the side stroke (say on the left side), the left arm is advanced in a curve, and made to describe the upper side of an ellipse, as represented at a b of fig. 43. This done, the right arm and legs are employed as propellers, the right arm and legs making a powerful backward stroke, in which the concavity of the hand

FIG. 43.-Side-stroke Swimming.--Original.

is directed backwards and outwards, as shown at c d of the same figure. The right arm in this movement describes the under side of an ellipse, and acts in a nearly vertical plane. When the right arm and legs are advanced, some swimmers lift the right arm out of the water, in order to diminish friction-the air being more easily penetrated than the water. The lifting of the arm out of the water increases the speed, but the movement is neither graceful nor comfortable, as it immerses the head of the swimmer at each stroke. Others keep the right arm in the water and extend the arm and hand in such a manner as to cause it to cut straight forward. In the side stroke the left arm (if the operator swims on the left side) acts as a cutwater (fig. 43, b). It is made to advance when the right arm

1 The outward direction given to the arm and hand enables them to force away the back water from the body and limbs, and so reduce the friction to forward motion.

and legs are forced backwards (fig. 43, c d). The right arm and legs move together, and alternate with the left arm, which moves by itself. The right arm and legs are flexed and carried forwards, while the left arm is extended and forced backwards, and vice versa. The left arm always moves in an opposite direction to the right arm and legs. We have thus in the side stroke three limbs moving together in the same direction and keeping time, the fourth limb always moving in an opposite direction and out of time with the other three. The limb which moves out of time is the left one if the operator swims on the left side, and the right one if he swims on the right side. In swimming on the left side, the right arm and legs are advanced slowly the one instant, and forced in a backward direction with great energy and rapidity the next. Similar remarks are to be made regarding the left arm. When the right arm and legs strike backwards they communicate to the body a powerful forward impulse, which, seeing the body is tilted upon its side and advancing as on a keel, transmits it to a considerable distance. This arrangement reduces the amount of resistance to forward motion, conserves the energy of the swimmer, and secures in a great measure continuity of movement, the body being in the best possible position for gliding forward between the strokes.

of

In good side swimming the legs are made to diverge widely when they are extended or pushed away from the body, so as to include within them a fluid wedge, the apex which is directed forwards. When fully extended, the legs are made to converge in such a manner that they force the body away from the wedge, and so contribute to its propulsion. By this means the legs in extension are made to give what may be regarded a double stroke, viz. an outward and inward one. When the double move has been made, the legs are flexed or drawn towards the body preparatory to a new stroke. In swimming on the left side, the left or cutwater arm is extended or pushed away from the body in such a manner that the concavity of the left hand is directed forwards, and describes the upper half of a vertical ellipse. It thus meets with comparatively little resistance from the water. When, however, the left arm is flexed and drawn

towards the body, the concavity of the left hand is directed backwards and made to describe the under half of the ellipse, so as to scoop and seize the water, and thus contribute to the propulsion of the body. The left or cutwater arm materially assists in floating the anterior portions of the body. The stroke made by the left arm is equal to a quarter of a circle, that made by the right arm to half a circle. The right arm, when the operator swims upon the left side, is consequently the more powerful propeller. The right arm,

like the left, assists in supporting the anterior portion of the body. In swimming on the left side the major propelling factors are the right arm and hand and the right and left legs and feet. Swimming by the side stroke is, on the whole, the most useful, graceful, and effective yet devised. It enables the swimmer to make headway against wind, wave, and tide in quite a remarkable manner. Indeed, a dexterous side-stroke swimmer can progress when a powerful breast-swimmer would be driven back. In still water an expert non-professional swimmer ought to make a mile in from thirty to thirty-five minutes. A professional swimmer may greatly exceed this. Thus, Mr. J. B. Johnson, when swimming against time, August 5th, 1872, in the fresh-water lake at Hendon, near London, did the full mile in twenty-six minutes. The first half-mile was done in twelve minutes. Cæteris paribus, the shorter the distance, the greater the speed. In August 1868, Mr. Harry Parker, a well-known professional swimmer, swam 500 yards in the Serpentine in seven minutes fifty seconds. Among nonprofessional swimmers the performance of Mr. J. B. Booth is very creditable. This gentleman, in June 1871, swam 440 yards in seven minutes fourteen seconds in the freshwater lake at Hendon, already referred to. I am indebted for the details regarding time to Mr. J. A. Cowan of Edinburgh, himself acknowledged to be one of the fastest swimmers in Scotland. The speed attained by man in the water is not great when his size and power are taken into account. It certainly contrasts very unfavourably with that of seals, and still more unfavourably with that of fishes. This is due to his small hands and feet, the slow movements

of his arms and legs, and the awkward manner in which they are applied to and withdrawn from the water.

Swimming of the Turtle, Triton, Crocodile, etc.-The swimming of the turtle differs in some respects from all the other forms of swimming. While the anterior extremities of this

FIG. 44. The Turtle (Chelonia imbricata), adapted for swimming and diving, the extremities being relatively larger than in the seal, sea-bear, and walrus. The anterior extremities have a thick anterior margin and a thin posterior one, and in this respect resemble wings. Compare with figs. 36 and 37, pp. 74 and 76.-Original.

quaint animal move alternately, and tilt or partially rotate during their action, as in the sea-bear and walrus, the posterior

FIG. 45.--The Crested Newt (Triton cristatus, Laur.) In the newt a tail is superadded to the extremities, the tail and the extremities both acting in swimming.-Original.

extremities likewise move by turns. As, moreover, the right anterior and left posterior extremities move together, and reciprocate with the left anterior and right posterior ones, the creature has the appearance of walking in the water (fig. 44).