96 NINliTEENTH REPORT. 



entire radial distance, and is there no possibility of abrupt interruptions 

 such as occur in the temperature gradient of the atmosphere? 



William I'errel, much the most distinguished meteorologist that America 

 has produced, and the one to whom we owe the basic principle upon 

 which modern meteorology is founded, predicted as a corollary to his 

 theory of the winds the existence of whirls about the earth's geographic 

 poles surrounding areas of calm and low atmospheric pressure. As these 

 polar calms and whirls are an important feature of the present theory 

 of atmospheric circulation, it will be profitable to examine briefly their 

 evolution as a study in the psychology of theory. In the preface to his 

 general treatise upon the winds, Ferrel tells us how his attention was 

 first directed to this subject through reading Maury's "Plu'sical Geog- 

 raphy of the Sea, " the first edition of which appeared in 1855, while 

 the first essay of P'errel was published in 1856. From Maury Ferrel 

 learned, as he has told us, "that the pressure of the atmosphere is less 

 both at the poles and at the equator of the earth than it is over two 

 belts extending around the globe about the parallels of 30 north and 

 south of the equator." On making reference to Maury we find" that upon 

 the basis of recorded observations between the parallels of 1<0° and 5i° 

 south latitude the average barometer reading varies from 29.9 to 29.4 

 in passing from the lower to the higher latitude. With the gradient 

 obtained from this limited range, Maury has extended tlie curve as a 

 straight line to the geographic pole through a range of thirty-four degrees 

 of latitude or more than twice the observed distance, and obtained a 

 theoretical reading for the pole of twenty-eight inches of mercury. A 

 similar method applied to the northern polar region has supplied a less 

 marked gradient and a theoretic value for the barometer reading at the 

 northern geographic pole of 29.65 inches of mercury. 



Since this theory was promulgated, exploration has been extended to 

 both poles of the earth and has shown that but a short distance beyond 

 the latitudes which limited the data employed by Ferrel, the steadily 

 lowering pressure gives place to a rising barometer in the direction of 

 the poles. Studies of the free atmosphere by means of balloons in the 

 same high latitudes also indicate pretty clearly that no such whirls as 

 Ferrel assumed can exist. Yet so great has been the success of Ferrel's 

 theory as a whole that despite their contradiction by the facts, the polar 

 calms and whirls are still treated in the latest text-books of meteorology. 



The polar whirls of Ferrel are by no means a unique example of a 

 large conception in science receiving general support because however 

 carelessly constructed it was an attachment or rider to a still larger 

 theory. The triumph of the larger idea or the prestige of the author 

 due to some other achievement, has by its inertia carried the smaller 

 conception to general acceptance. 



