To the typical American boy every object he sees suggests to him possibilities of amusement, and to him an up-to-date bath-room is as full of such suggestions as a dictionary is of words. The great white tub affords an excellent sea for his gun-boats to do battle upon, or offers a straight-away course over which his home-made yachts may sail, while a fan fills their sails with everything from a light breeze to a ripping gale. What boy has not discovered, for himself, that The Bath-tub is a Splendid Receiving-Tank for the occasional water-animals captured by him in creek or pond, or at the fish-market? The laundry tubs are also useful and, not being in demand as frequently as the bath-tub, are for this reason often more convenient. If the grown people would only let the bath-room alone, there is no end to the fun which an ingenious lad could have in that useful little room. As a Lake for His Fleet, and as a receiving-tank for his water-pets are only two of the uses which the bath-tub suggests to a bright boy. When he sees the faucet he realizes that this can afford him power for all sorts of machinery, if he can arrange a water-wheel under it to transmit the power. Every country boy knows how to make water-wheels, and every summer the springs and brooks all over the land turn these little wheels in exactly the same manner which the larger streams turn the big wheels for the factories and mills on their banks. But there are thousands of boys in our great cities who have never seen A Water-wheel, and for the use of these boys the accompanying illustrations were drawn. [Illustration: FIGS. 139-141.] Fig. 139 shows a four-sided soft-pine stick, with square ends, and if you have a good sharp knife it requires but little work to trim off the four edges of this stick until it has the form of a six-sided lead-pencil (Fig. 140), after which but little skill is required to whittle the ends down to the size of the hole in a thread-spool (Fig. 141). The Shaft. You will see, on examining the illustration, that the middle is left with the six sides untouched. An Old Cigar-Box will not only furnish you with excellent wood for the paddles of your wheels (Fig. 142), but, if carefully taken apart, it will also furnish you with just the right sort of nails with which to fasten your paddles to the shaft. [Illustration: FIG. 142.] Make Six Paddles, all of the same size and same pattern, and nail one to one of the six sides of the shaft (Fig. 142). Turn the shaft around to the next face or side, and nail another paddle in place; continue this work until you have the paddle-wheel shown in Fig. 143. [Illustration: FIG. 143.] On to one or both ends of the shaft you may now slip wooden spools, pushing them up the stick until they fit tightly, and leave a projecting end of the shaft sticking out of the end of the spool. Hanging-Bars.