Some thirty years ago a certain boy built a “switchback” in his back-yard, very much like the one here described, and great fun he had with it; but as he was not rich, and the lumber cost him something, he issued a number of tickets at one cent each, every ticket entitling the holder to three rides on the “switchback.” In this way he was soon repaid all the expense he had been under during the erection of his wonderful railroad. This is what that boy told the writer, and as the former young engineer is now no longer a lad, but a grave D.D., who wears solemn black clothes and preaches long sermons, the writer believes him. [Illustration: Under Full Headway.] But whether you charge a cent, a marble, or nothing, for a ride, you and your friends are bound to have a rollicking good time on the back-yard “switchback.” CHAPTER XV. HOW TO BUILD A TOBOGGAN-SLIDE IN THE BACK-YARD. Toboggans and sleds are not always used on snow and ice, neither is coasting confined to winter weather. At most of the summer resorts you may coast down an artificial hill, upon real toboggans, over a slide of hard-wood rollers, and end with a whoop and a splash in the water of the bathing-pool. Slipperies. All through the southwestern part of this country the summer drought causes the rivers to subside, leaving more or less high mud or clay banks, which are utilized by the youngsters as mud-slides, and called by them “slipperies.” The boys use neither sled nor toboggan, but make a slide by pouring water over the dry mud until they have a long, slippery track, down which they coast, ending with a splash in the river. A War-Time Slippery. A good many years ago a battalion of Union soldiers were camped on the river-bank, near where some Kentucky boys were having fun on a long slippery, and one day, before the lads knew what had happened, two thousand naked men suddenly made their appearance, jostling each other, for a slide down the mud-track. It was a great sight to see these men-children coasting down the mud-bank, and the show the soldiers made for them repaid the boys for their labor in building the slide. [Illustration: FIG. 138.--The Toboggan-Slide.] Tropical Toboggan-Slide.