Page:Popular Science Monthly Volume 91.djvu/598

 Up with the Storm Signals

The language of the weather bureaus of the world is one of flags, lights and cones

��THE invention of the electric telegraph made it possible for meteorologists to gather reportsof simultaneous weather observations over exten- sive areas, enter the data on charts, prepare fore- casts and storm warn- ings, and issue such in- formation to the public; all within a period of time short enough to make the predictions use- ful for practical purposes. Telegraphic weather ser- vices date from the middle of the last century, and at first they were designed especially for warning mariners of approaching storms. In the days before "wireless" the problem of transmitting such warnings to ships at sea could be solved only by the display of con- spicuous signals at nu-

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��NORTHERLY GALES

��SOUTHERLY GALES

��GALES FROM K. E.

��GALES FROM S. E

��HURRICANE

��A combination o f cones which is seen in
 * most French charts

���A standard storm-signal tower of the U. S. Weather Bureau. At the top of the mast is a weather vane

��merous points along affected seacoasts. Several forms of signal were evolved. In

the British Isles Admiral FitzRoy intro- duced the use of canvas cones and "drums" (i. e., cylinders), which, seen from any direction, pre- sented the appearance of solid triangles and squares against the background of the sky. At night they were replaced by groups of lanterns. The drum, indicating winds of varying direction, has since been abandoned, and the British now use the cone alone, pointing up or down, for northerly or southerly gales, re- spectively.

One of the earliest storm-signaling devices was a form of semaphore, known as the "aeroclino- scope," used in Holland. The position of the arm of the semaphore indi- cated the region in which the barometer was low; i. e., the storm center. The American storm-flag — red with a square black center — was adopted by the United States Signal Service (the predecessor of the Weather Bureau) in 1 87 1. This signal was later amplified by the addition of red and white pennants, to show the

����Cone pointing down indi- cates southerly gale; cone pointing up, northerly gale

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��At night triangular groups of Ian • terns of the same significant arrangement replace the cones

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