WEATHER SIGNALS. Adopted for general use by the United States Signal Service on and after March 1,1887. INTERPRETATION OF SIGNALS. No. 1, white flag, clear or fair weather, no rain. No. 2, blue flag, rain or snow. No. 3, black triangular flag, refers to temperature, and above Nos. 1 or 2, indicates warmer weather; below Nos. 1 or 2, colder weather, and when not displayed, stationary weather. No. 4, white flag with black center (cold wave flag), sudden fall in temperature ; this signal is usually ordered at least twenty- four hours in advance of the cold wave. It is not displayed unless a temperature of forty-five degrees, or less, is expected, nor is flag No. 3 ever displayed with it. A red flag with a black center indicates that a storm of marked violence is expected. DISPLAY EXAMPLES. When displayed on poles, the signals should be arranged to read downward ; when displayed from horizontal supports, a small streamer should be attached to indicate the point from which the signals are to be read PRESIDENTS OF THE UNITED STATES.