Weather Study 859 



friend in Boston to take observations of a lunar eclipse at the same time 

 that he, himself, was to take observations at Philadelphia. On the night of 

 the eclipse a terrific northeast wind and rain storm set in at Philadelphia, 

 and Franklin was unable to make any observations. He reasoned, that as 

 the wind blew from the northeast, the storm must have been experienced in 

 Boston before it reached Philadelphia. But imagine his surprise, when he 

 heard from his friend in Boston that the night had been clear and favorable 

 for observation, but that a fierce wind and rain storm set in on the following 

 morning. Franklin determined to investigate. He sent out letters of 

 inquiry to all surrounding mail stations, asking for the time of the beginning 

 and ending of the storm, the direction and strength of the wind, etc. When 

 the information contained in the replies was charted on a map it showed 

 that, at all places to the southwest of Philadelphia, the beginning of the 

 storm was earlier than at Philadelphia, while at all places to the northeast 

 of Philadelphia the beginning of the storm was later than at Philadelphia. 

 Likewise, the ending was earlier to the southwest and later to the northeast 

 of Philadelphia than at Philadelphia. He also found that the winds in 

 every instance passed through a regular sequence, setting in from some 

 easterly point and veering to the south as the storm progressed, then to the 

 southeast and finally to the west or northwest as the storm passed away and 

 the weather cleared. 



A further study of these facts convinced Franklin that the storm was an 

 eddy in the atmosphere, and that the eddy moved as a whole from the 

 southwest toward the northeast, and that the winds blew from all directions 

 toward the center of the eddy, impelled by what he termed suction. 



Franklin was so far in advance of his time that his ideas about storms 

 made little impression on his contemporaries, and so it remained for 

 Redfield, Espy, Loomis, Henry and Maury and other American meteorolo- 

 gists, a hundred years later, to show that Franklin had gained the first 

 essentially correct and adequate conception of the structure and movement 

 of storms. 



During the first half of the nineteenth century, considerable progress 

 was made in the study of storms, principally by American meteorologists, 

 among whom was William Redfield of New York, who first demonstrated 

 that storms had both a rotary and progressive movement. James Espy 

 followed Redfield in the construction of weather maps, although he had 

 already published much on meteorological subjects before the latter entered 

 the field. 



Professor Joseph Henry, Secretary of the Smithsonian Institution at 

 Washington, was the first to prepare a daily weather map from observations 

 collected by telegraph. He made no attempt to make forecasts, but used 

 his weather map to demonstrate to members of Congress the feasibility of a 

 national weather service. 



An incident occurred during the Crimean War that gave meteorology 

 a great impetus, especially in Europe. On November loth, 1854, while 

 the French fleet was at anchor in the Black Sea, a storm of great intensity 

 occurred which practically destroyed its effectiveness against the enemy. 

 The investigation that followed showed that the storm came from western 

 Europe, and had there been adequate means of communication and its 

 character and direction of progress been known, it would have been 

 possible to have warned the fleet of its approach and thus afforded an 

 opportunity for its protection. 



