The paper may be selected in several colors, and the gores cut from these, pasted “in alternately, will produce a pretty array of colors when the balloon is in flight.  The shape of a good balloon is shown in Fig. 1.  The gores for a 6-ft. balloon should be about 8 ft. long or about one-third longer than the height of the balloon.  The widest part of each gore is 16 in.  The widest place should be 53-1/2 in. from the bottom end, or a little over half way from the bottom to the top.  The bottom of the gore is one-third the width of the widest point.  The dimensions and shape of each gore are shown in Fig. 2.

The balloon is made up of 13 gores pasted together, using about 1/2-in. lap on the edges.  Any good paste will do—­one that is made up of flour and water well cooked will serve the purpose.  If the gores have been put together right, the pointed ends will close up the top entirely and the wider bottom ends will leave an opening about 20 in. in diameter.  A light wood hoop having the same diameter as the opening is pasted to the bottom end of the gores.  Two cross wires are fastened to the hoop, as shown in Fig. 3.  These are to hold the wick ball, Fig. 4, so it will hang as shown in Fig. 5.  The wick ball is made by winding wicking around a wire, having the ends bent into hooks as shown.

The balloon is filled with hot air in a manner similar to that used with the ordinary cloth balloon.  A small trench or fireplace is made of brick having a chimney over which the mouth of the paper balloon is placed.  Use fuel that will make heat with very little smoke.  Hold the balloon so it will not catch fire from the flames coming out of the chimney.  Have some alcohol ready to pour on the wick ball, saturating it thoroughly.  When the balloon is well filled carry it away from the fireplace, attach the wick ball to the cross wires and light it.

In starting the balloon on its flight, take care that it leaves the ground as nearly upright as possible.  —­Contributed by R. E. Staunton.

** A Simple Steamboat Model [216]

The small boat shown in the accompanying sketch may have a length of 12 to 18 in. and is constructed in the

[Illustration:  Sectional View and Completed Boat]

following manner:  A small steam boiler, A, is supported by two braces over an alcohol lamp in the middle of the boat.  A small pipe is fastened to the top of the boiler in such a way that the open end will be opposite the open end of another pipe, B, somewhat larger in size.  The pipe B opens into the stern of the boat at C, as shown in Fig. 1.  The steam, coming through the small pipe A, is driven forcibly through the larger pipe B, and carries with it a certain amount of air out through the opening C into the water.  As the boat is driven forward by this force, the steam arises to the surface in the form of bubbles.  The boat soon attains considerable speed, leaving a long wake behind.

** To Remove Grease from Machinery [216]