=Fig. 22. The Northwest Storm Warning.= A white pennant above a square red flag with black center displayed by day, or a white lantern above a red lantern displayed by night (Fig. 22A), indicates the approach of a storm of marked violence, with winds beginning from the northwest. =Fig. 23. Hurricane, or Whole Gale Warning.= Two square flags, red with black centers, one above the other, displayed by day, or two red lanterns, with a white lantern between, displayed by night (Fig. 23), indicate the approach of a tropical hurricane, or of one of the extremely severe and dangerous storms which occasionally move across the Great Lakes and Atlantic Coast. [Illustration: Fig. 25 ] We have installed at our manufacturing plant a high-class weather station, with equipment of the latest United States Weather Bureau standard pattern, and are able to send out weather signals by wireless from our own wireless station twice daily, at 4 P. M. and 7 P. M., to all boys owning a wireless outfit. The indications are taken from our own instruments. A description of these instruments and the method of recording the indications will give you an insight into how the various government weather stations arrive at their forecasts. [Illustration: Fig. 26 ] On the roof of the factory is a weather vane (Fig. 34) twenty feet high, which is connected electrically with a register in our weather office. The register is of the quadruple type (Fig. 45), and is capable of recording wind direction, wind velocity, rainfall, and sunshine on the same form or sheet. Thus, we know the wind direction and can deduce certain things relating to the weather. Mounted on the wind vane support is an anemometer (Fig. 36), an instrument for measuring the velocity of the wind. A rain gauge (Fig. 49) on the roof catches the precipitation, and for every one hundredth of an inch of rainfall, a small tipping bucket empties its contents into a receiver and a record is made on the form in the quadruple register. The same pen that records the rainfall also records the number of hours of sunshine during a day, for it is not a common thing to have rain and sunshine at the same time. A hygrothermograph (Fig. 43) records on a form the temperature and amount of humidity in the atmosphere. A barograph (Fig. 44) records the pressure of the atmosphere. For determining the pressure, we also have a mercurial and aneroid barometer, which will be described later on. You can readily see that it is a simple matter to obtain the weather indications. [Illustration: Fig. 27 ] CLOUDS The numberless kinds of clouds makes it quite difficult to describe and arrange them or illustrate them in any manner that makes it easy to recognize them. Although some may be recognized from description and with a fair amount of observation, you will be able to classify them in their proper place. For instance, the thunder clouds most anyone recognizes without any experience whatever.