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. . . and the air loses heat. To disinfect the cooled air, Latimer suggested adding some disinfectant solution to the water tank. You can quickly build a similar cooler to place on your window sill. Will it work? Yes indeed . . . providing you try it on a low-humidity day.

On a hot, humid day the cooler won’t work efficiently because the water will not evaporate readily. Make the frame out of “two-by-two” wood stock (the wood you buy will actually measure about 1¾ inch square). A 6-foot length will be enough. The drawing shows the lengths of the main frame pieces and of the four corner legs. Screw or glue the frame together, then cement the metal cake pan on top of the frame. Be sure to use waterproof glue such as epoxy. The screen is a piece of cheesecloth, about 18 inches long and 12 inches wide. Fasten the screen to the frame with a few thumbtacks. Drape the top of the screen into the metal pan. Now fill the pan with water and place the cooler in an open window, or better, in front of a small electric fan. Put a metal cookie sheet underneath the cooler to catch drips. Dab some water on the screen to moisten it uniformly. Observe that air moving through the screen gets somewhat cooler. How much cooler? That depends on the speed of the moving air and the humidity. If you wish you can check how well your project works by placing a thermometer in front of the “cooler” and a second one on the opposite side.