On Chart 5 a line of arrows extends from the storm center westward to Wyoming, where the storm originated. A small cross inclosed by a circle marks its western extremity. Another cross located near Cheyenne shows where the storm center was located twelve hours after its origin. A third cross gives it location near Des Moines twenty-four hours after it started eastward. It was here that we began the study of this storm on Chart 3. A cross near Chicago indicates the distance traveled by the center during the third twelve hours, and Chart 5 shows its progress during the fourth twelve-hour period. When the storm was central at Cheyenne the danger warnings for mariners were displayed at all ports of the Great Lakes, as the forecaster knew that in accordance with general laws the storm must move toward the east. When it was centered at Chicago, danger warnings were displayed on the Atlantic coast from North Carolina to Maine, as it was known that long before the storm reached the ocean the in-rush of wind toward the storm center would cause a dangerous on-shore gale and the breaking of heavy seas on the shore line. All craft that could be reached with the danger signals made safe in port, except the great ocean liners, which are of such strength as to safely withstand almost any storm. A special set of observations ordered by the Washington office of the Weather Bureau from its stations in the region of the storm, and well in advance of it, kept the chief forecaster informed as to the progress of the cyclone, and before the storm center reached the coast the danger signals communicated to mariners the fact that the winds would soon shift to northwest as the center of the disturbance passed out to sea. The reader’s attention will now be directed to the red lines on Chart 5; they pass through places having the same temperature, but for simplicity the readings of temperature, whereby these lines were located, are omitted from the printed chart. Observe the line marked 40°; it passes across southern New England to western New York, but when it reaches the center of the storm it encounters the cold northwest winds blowing into the storm on its west side and is forced southward to Texas. Charts 3, 4, and 5 give a graphic history of one severe winter storm. In summer such general storms do not often occur. They are frequent in spring and fall, but of higher temperature and less severity than in winter. In summer Lows drift sluggishly across the continent; the barometer at the center of the cyclone is usually not more than two to four tenths of an inch below the pressure of the Highs, and the rain, instead of falling in a broad sheet, as shown by the shading of charts 4 and 5, falls in numerous sporadic outbursts, each of which is but a few square miles in area, their combined surfaces usually covering only a part of the region over which passes the Low.