Swimming on a trolley-line sounds like an impossibility. It is a very real practical feat, nevertheless, and hundreds of New-Yorkers can tell you all about it from their own experience. No other way of learning how to swim is half so pleasant as the trolley-line plan. There is no fear of bobbing under and losing your breath and swallowing a quart of water. Once you buckle on your trolley belt, there you are, and there you stay, right on the surface of the water. It is as safe as sitting in a rocking-chair, and a thousand times more fun. Fred L. Balmes, a young swimming-teacher, invented the trolley plan. He found that the usual scheme of putting a belt around the pupil's chest, running a line from the back of it to the end of a long pole, and then towing the pupil along like landing a big fish, was not apt to encourage learners. They always feared that the teacher would stub his toe, or look around suddenly, or in some other way forget to hold up the end of the pole. That, of course, meant a ducking; and a beginner in the gentle art of swimming would rather suffer ten beatings than one ducking. Nobody ever learned well by wearing an inflated rubber life-belt. The belt has too much floating power, and boys who wear one when beginning always kick too high thereafter, and send their feet splashing above the surface, which is very bad form. When I was a boy we used to go down to the Sandy Flats, where there was a long stretch of river only three feet deep. An expert (a boy who could swim about ten yards) upheld the pupil's chin on the palm of his hand, and yelled, "Now kick like a bull-frog!" If the pupil was too embarrassed to do this immediately and successfully, the expert always popped him under, and when he came up spluttering and shrieking, sent him down again for luck. The system was perfect--all but the cruel ducking. [Illustration: HE MIGHT LIE THERE ALL DAY WITHOUT WETTING HIS MOUTH.]