STORMS, HUIiRICANES, AND TYPHOONS. 



421 



in the barometric pressure would create a breeze with a velocity 

 of seven miles the hour. Such a wind is capable of exerting a 

 horizontal pressure of 0.2 lb. the square foot, thus : 



Changes, however, in the barometer, amounting to live or six 

 times these diiferences, are observed to take place at sea without 

 producing winds exceeding in velocity the rates above. This is 

 because the places of high and low barometer at sea are far apart, 

 and because, also, of the obstructions of the winds afforded by 

 the inequalities of the earth's surface. 



790. Predicting storms. — But, in this view of the subject, the 



importance of a daily system of weather reports by telegraph on 



shore, and across the water between Europe and America when 



the sub- Atlantic cable is well laid, looms up and assumes all the 



proportions of one of the great practical questions of the age. 



^\'e may conjecture, as the probable result of observation, that 



the greater the distance between the place of high and low 



barometer, the less the velocity of wind for a given barometric 



ditierence would be. Professor Buys Ballot has discovered,, 



practically, the numerical relation between the force of the wind 



and given barometric differences for certain places in Holland. 



With the view of ascertaining like relations for this country, it 



has been proposed to establish a cordon of meteorological stations^ 



over the United States, each station being required to report 



daily to the Observator}^ in Washington, by telegraph, the height 



of the barometer, force of wind, etc. By such a plan, properly 



organized, we might expect soon to be able to give the ships ^ 



not only on the great lakes, but in our sea-port towns also, 



timely warning of many a gale, and to send by telegraph to 



Europe — when one shall be paid — warning of many a one long 



before it could traverse the Atlantic. The contributions which 



the magnetic telegraph is capable of making for the advancement 



