HOW TO BUILD - AND USE! - A SOLAR STILL

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Smooth the ends of the bottom tube that will support the toweling and insert it in place . . . and you're ready to sew the toweling together. The still in our plans uses a towel 24 inches wide, with the ends lapped and sewed in two places (along both edges of the lap) to make a loop. In measuring for this, make the loop slightly smaller than the distance between the tubes, because the towel will stretch somewhat when wet. Too much sag would cause it to touch the back of the box and thus contaminate the distilled water.

With the towel sewed together and dampened, slip the 1/2-inch tubes halfway out and start the towel loop onto the supports inside the box (see Fig. 2). The bottom tube is slid back into place first, then the top one is carefully raised into position and forced back into the 3/4-inch hole. Adjust the towel so that it covers the entire length of the tubes and is smooth. Do not let it touch the sides of the box.

At this point, remove the top 1-by-4 piece so that the dimensions for the box's glass front can be taken. Slide a heavy piece of cardboard into the grooves and trim it to fit. Then have your supplier cut a pane of glass to the size of the pattern. The grade of window glass known as "water-white" allows more of the sun's rays to pass than an ordinary pane does and is therefore more efficient for our purpose. However, if it's not available, standard single-strength glass will do.

Slide the glass into position. Make sure it's as clean as it can be . . . particularly on the inner surface, which will not be easy to reach when the still is assembled. Detergents may interfere with proper forming of droplets on the glass, so use plain water for cleansing.

Handle the glass very carefully to avoid cutting yourself on its sharp edges. With the still at a 45-degree angle, start the glass into the slots and ease it downward. When it contacts the aluminum foil at the bottom groove the glass should force the foil neatly into place. Replace the top piece of wood, tighten the screws and the still is ready for operation.

Distillation is easy with our solar plant. First, orient the unit so that the- sun's rays strike it as close to a right angle as possible. Mount the still on a level surface so that the uneven legs will give it the proper slant for draining. If the reservoir can is not vertical, carefully twist the container until it is. The towel should be snug enough to hold it, and the force fit of the end cap in the 3/4-inch hole also helps in this respect.

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