1 piece of metal marked off in de- middle of the trough from end to Fig. 3. Trough-dial. This is formed of a Fig. 4. Horizontal Dial. This is more common than the others just described, but is harder to make because the dial is not divided into equal parts. To make one exactly requires the use of mathematics, but one can be made roughly as follows: Fix a disk or square plate of zinc on a post, so that it will be perfectly level, and in the middle drive a pin for a style, inclined as before in the direction of the north star. The triangle in Fig. 2 may be cut out of zinc and soldered to the dial, its edge AC answering as a style. Watch the shadow of the style, and mark each hour on the edge of the dial where the shadow falls at that hour. Only the time used must be sun time-not true time. The difference between these two sorts of time will now be explained. Correction. If the earth moved around the sun at a uniform speed, the sun dial would always indicate the true time, but it moves faster at some times than at others, so that a correction must usually be added to or subtracted from the hour it points out, and the same correction must be used in marking the hours on the dial. A table of these corrections (expressed in minutes) is given below. All corrections marked + are to be added to the reading of the dial to get the true time, and all marked - are to be subtracted. In marking the dial, where it is necessary to get sun time from true time, the corrections marked - are added to the pieces of glass together, smoked side inward, by elastic bands, keeping them apart by slips of paper pasted at the ends, so that the smoked side will not rub. The pieces of glass can now be fastened over the eye-pieces of the operaglass by a large elastic band around the middle. The spots can now be seen easily. When a spot shaped so that it can be recognized is seen, it should be watched from day to day, and will be seen to change its place. The reason is that the sun is turning on its axis like the earth, carrying the spot around with it. The average number of sun-spots does not remain the same, but is greatest every eleven years. The last year when there was the largest number was 1881, and the next will therefore be in 1892. Until about that time there will be more and more of them, and then they will decrease in number till about 1897, when they will begin to increase again. SWAYKA, a game played by any number of persons with an iron pin eight or nine inches long, and any number of iron rings varying in diameter from two inches to one foot. The pin, which is called the Swayka (its name in Russian), is so sharp that it will stick upright when thrown either at the ground or a board floor. The rings are placed in any order on the ground, and the players try to throw the Swayka so that it will stick upright within one of them. Their object is so to place it in each one of the rings in any order. RULES. 1. The players take turns, each having only one throw in a turn. 2. A player may throw first at whichever ring he chooses, but he must announce beforehand which one it is, and if he throws the Swayka into any other it counts as a miss. 3. Whoever can place the Swayka in all the rings in regular order of size, beginning with the smallest and ending with the largest, receives the name of King, has general control of the game, acts as umpire, and has the right to order any one to pick up the Swayka for him. When he reaches the largest he must begin at the smallest again, otherwise he cannot remain King. He holds the title as long as he can throw successfully in that order. If two or more players earn the right to be King they must throw together, the other players omitting their turns till all but one have missed. 4. No player may throw a second time at the same ring till he has placed the Swayka in all the other rings. 5. When a player misses, all the rings he has thrown into count for nothing, and he must throw, at his next turn, into the next larger ring. If he miss that, he must take the next larger at his following turn, and so on till he is successful or misses the largest ring. 6. Whoever misses the largest ring is out of the game, and is obliged to pick up the Swayka for his companions till some one else misses that ring and takes his place. 7. The game may last as long as desired. If so agreed, he who has been King the greatest number of times during the play is victor. Swayka is a Russian game, and is said to be very popular in that country. SWEDISH WHIST. See PREFER ENCE. SWIMMING, the art of propelling one's self through the water by the arms and legs. will thus, after practice, be able to enter the water without gasping, and will learn that it is easy to keep his body afloat by a very slight push of the hand against the bottom, as shown in Fig. 1. He should try to open his eyes under water, and when he puts his head out he must remember to breathe outward before inhaling, thus expelling the water from his nostrils. After he has acquired confidence, he should wade out to a depth of about four feet, and try to swim to shore, using the simple chest stroke, or swimming "dog-fashion," as explained below. At first he will probably splash about rather aimlessly with hands and feet; but as soon as he sees that he can keep himself afloat, he will be able to follow directions more exactly. When he sinks he can sustain himself by pushing with one hand against the bottom-but this should be done as seldom as possibie. When he can swim a few strokes without this aid, he should begin at a greater distance from shore, and so on, until he is perfectly at home in the water. This will probably be only after much patient practice, though some learners make faster progress than others. This is not the only way of learnLearning to Swim. The learnering to swim. Some people advise should choose, if possible, a grad- the learner to jump at once into ually sloping shore with gravelly water over his depth, trusting to or sandy bottom, where there is his instinct and to his natural strugno current. If he is not used to gles to get to shore; but this should the water, he must first accustom never be tried unless some older himself to being under it by ly-person is near to rescue the swiming down on the bottom, where it mer in case of need. Timid people is only one or two feet deep. He should never try it at all. Another method is for a teacher or companion to support the learner, by plac Fig. 2. ing a hand beneath him till he has learned to make the proper motions and is able to keep himself up. In another method a band around the learner's chest is fastened by a rope to the end of a pole held by an assistant (see Fig. 2), who thus gives the swimmer aid as long as he needs it. Some teachers say that the learner ought to practise his strokes lying across a chair, before he tries them in the water, but others consider this unnecessary. The various kinds of swimming strokes will now be described. Breast-stroke. This is the ordinary stroke and the one generally used by learners. Fig. 3 shows the position of starting as seen from above, and Fig. 4 the attitude as seen from one side. The hands are brought under the chin, fingers together, and palms down and slightly hollowed. The arms are then pushed straight forward, keeping the hands together till they are at full length. The hands are now line with the shoulders, when the separated and brought obliquely hands are brought in edgewise till backward and downward (called they are together just beneath the "striking out") till the arms are in chin, as at first. Some swimmers take a longer stroke than this, bringing the hands down as far as the hips. While the hands are making Fig. 3. this stroke, the feet and legs make a corresponding one. The knees are bent so that they will be as far apart as possible, while the feet are together, and the legs are then kicked back and out so that the soles of the feet press flatly against the water. The legs must then be closed stiffly, like a pair of scissors, forcing the water out from between them, and so pushing the swimmer forward. When they are closed the knees must be opened again as at first. The arm and leg strokes must be made at the same time, the feet being drawn up as the hands are advanced, the kick being made quickly as the hands begin to strike out, and the legs being closed when the hands have about half finished the stroke. Fig. 4 shows the proper angle for the body to make with the water surface. The head should be kept back as far as possible, that it may be supported by the lungs. The breath should be in time with Fig. 4. ply kicks with them. the stroke, the lungs being empty | uses his legs properly than if he simwhen it is being made, and full when the swimmer is drawing in his limbs for a new one. The reason for this is that the body is lighter when the lungs are full of air, and there is greatest need of their sustaining power between strokes. Beginners are apt to place most reliance on the arm movement, paying little attention to the legs; but the leg stroke is really as important as that of the arms, or even more important, as some teachers think. The swimmer will be able to go much farther without tiring himself if he Side-stroke. The swimmer lies on his side instead of his breast. Either side may be used, but most swimmers prefer the right, since the right arm can then be used to the greatest advantage. The head is turned so that the chin rests against the uppermost shoulder, and lies as deeply in the water as possible. The face may be kept above water, or it may be above only when the forward impulse raises it a little. The lower hand is advanced under water on a level with the head, and |