December 31, 1920] 



SCIENCE 



639 



points out the relations existing between the 

 tides at various Gulf stations and the position 

 of the hurricanes in the Gulf. He is enabled 

 by these studies to show the portion of the 

 storm in which the greatet wave-producing 

 winds occur. The quotation from John Eliot's 

 " Cyclonic Storms in the Bay of Bengal " re- 

 garding the wave-producing power of the hur- 

 ricanes is worth repeating here: 



Whatever explanation be adopted of the produc- 

 tion of these large waves, there is no doubt of the 

 general principle that air moving over a water sur- 

 face always produces waves, and that the magni- 

 tude of the waves is dependent upon the extent of 

 the water area over which they blow and upon the 

 force of the winds. It is evident that the strength 

 of the swell or the distance at which it will be 

 sensibly felt in the open sea, will depend partly 

 upon the strength of the producing winds and 

 partly upon the distance over which the producing 

 winds act with no considerable change in direction. 

 The rapid movement of the air over the surface of 

 the sea gives rise, by some species of cumulative 

 action to a continuous succession of large parallel 

 waves so long as the winds are fairly steady in 

 character. Waves that are produced in this man- 

 ner travel steadily onward in the same general di- 

 rection so long as they meet no obstruction, and if 

 they pass beyond the area of strong winds, they 

 decrease slowly in height and force. 



It was noted by Mr. Eliot that in the Bay of 

 Bengal the swells were observed 400 miles 

 from the center of the storm and forty-eight 

 hours before its arriTal. 



Dr. Cline has given a diagram of the type 

 of waves and swells which emanate from a 

 hurricane, and he finds that the greatest waves 

 are produced in the rear right-hand quadrant 

 of the storm and travel forward through the 

 storm and make themselves felt far in front 

 and mostly to the right side of the line of ad- 

 vance at the time the wave left the storm. 

 These waves travel in the direction of the 

 storm's motion. Waves of lesser amplitude 

 are sent out to the right and left of the 

 center of advance of the storm in the front 

 half, still smaller, weaker waves are sent out 

 to right and left in the rear of the storm; 

 and finally, the weakest waves of all are sent 

 out in the rear. 



How intense the winds are in the rear right- 

 hand quadrant of the advancing hurrricane 

 may be seen from the following (indicated) 

 wind velocities observed at Burrwood, La., 

 near the mouth of the Mississippi Eiver, upon 

 the occasion of the hurricane of September 29, 

 1915: 



Sixty miles per hour or above prevailed for a 

 .period of 13 hours. 



Seventy miles per hour or above prevailed for a 

 period of 12 hours. 



Eighty miles per hour or above prevailed for a 

 period of 11 hours. 



Ninety miles per hour or above prevailed for a 

 period of 3 houra. 



One hundred and eight miles per hour prevailed 

 for a period of 2 hours. 



One hundred and sixteen miles per hour pre- 

 vailed for one third of an hour. 



There was a gust with 1 mile at the rate of 140 

 miles per hour. 



It appears that as these waves begin to 

 reach the coast there is a piling up of water, 

 which is, of course, in excess of the normal 

 predicted tide. By carefully noting and com- 

 paring the high water at various stations it is 

 possible. Dr. Cline believes, to detect changes 

 in direction of movement of the disturbance. 

 As an example of this, and also of the fact that 

 the rise of water precedes any change in the 

 barometer, he cites the case of the storm of 

 September 11-14, 1919, in which the " barom- 

 eter at Burrwood, New Orleans, Galveston 

 and Corpus Ohristi was either stationary or 

 falling only a few hundredths of an inch, the 

 water, first at Burrwood, later at Galveston, 

 and then at Aransas Pass was rising in feet, 

 telling the story of the movement and of the 

 change in the course of the storm as plainly 

 as could be told." 



By this method it is possible to tell whether 

 the storm is shifting its course to right or left 

 by the shifting of the point of greatest rise 

 to right or left. The regular tides are not 

 obscured by these storm tides except perhaps 

 in the last twelve hours before the storm 

 strikes, when there are other features of prog- 

 nostic value which can be relied upon. The 



