Many persons are familiar with the experiment of seeing the air by looking across a heated surface. The following method of "seeing the wind" is pronounced even more interesting: Take a polislied metallic surface with B straight edge - a large handsaw will answer the purpose. Choose a windy day, whether hot or eold, clear or cloudy, only let it not rain or the air bemurky;in other words, let the air be dry and clear, but this is not essential. Hold your. metallic surface at right angles to the direction of the wind, namely, if the wind is north hold jour surface east and west, bu instead ol' holding the surface veratioally, incline it about 45 degrees to the horizon, so that the wind, striking, glances and flows over the edge (keeping it straight) as water over a dam. Now sighr carefully over the edge at some minute and sharply defined object, and you will see the air flowing over as water flows over a dam. Make your observations carefully and you will hardly fail to see the air, no matter how cold. The result is even better when the sun is obscured.