294 



SCIENCE 



[Vol. LV, No. 1420 



seasonal control of certain industries, are onlj^ 

 suggestions of the many economic considera- 

 tions dependent in a large way upon the geo- 

 graphical distribution of monthly mean tem- 

 perature. 



In. mid-summer, however, the south to north 

 gradients of temperature in the east are not 

 so marked as in winter. "So far as the mean 

 temperatures alone are concerned, therefore, 

 a long journey from south to north in search 

 of decidedly cooler summers gives far less 

 change than the corresponding trip from north 

 to south in winter in search of much warmer 

 and balmier climates." Three features of Pa- 

 cific coast temperatures are interesting: (1) 

 the slight north-south gradient of only 1° F. 

 per 100 miles along the coast; (2) the ex- 

 tremely steep gradient from the cool coast of 

 southern California to the heated interior; and 

 (3) the contrast between heated valleys and 

 cool slopes. 



But it is in his discussion of the annual march 

 of the isotherms that Professor Ward waxes 

 especially cinematographic, for one can see 

 the northward and southward march of the iso- 

 therms as vividly as if they were projected 

 upon the silver sheet. As the winter advances 

 these isothermal lines appear in northerly lati- 

 tudes and glide smoothly and continuously 

 equatorward, and later begin their poleward 

 migration, sometimes leaving the earth's surface 

 entirely in higher latitudes, and rising into the 

 free-air. This is the author's conception of the 

 interpretation of such charts, and concern- 

 ing it, he remarks : 



When tills conception is thoroughly in mind, 

 isothermal maps have a new meaning. They are 

 no longer dead and rigid, but are full of move- 

 ment, suggesting an infinite number of relations 

 between the everchanging temperature and all of 

 human life and activity. 



The temperature gradient in January from 

 southern Florida to Laborador is the steep- 

 est in the world, when the great distance is 

 considered. This steep gradient, especially 

 unique because there are no transverse mount- 

 ain ranges to produce it, has great economic 

 significance, as was first pointed out by Woei- 

 kof. Labrador is arctic in climate, while Flo- 



rida in many respects is tropical. This 

 favored the prosperity of the early colonists 

 and remains of the greatest economic signifi- 

 cance. 



The final portions of the paper deal with 

 many questions of considerable popular interest. 

 Upon what does our judgment of an abnor- 

 mally cold or warm month depend? Cei'tainly, 

 our senses are not capable of averaging a 

 month's temperatures so that they can con- 

 clude that this month or that was abnormally 

 waiTR or cool. Such opinions, it seems, are 

 based upon extreme "spells" of weather, their 

 severity, and their distribution. 



What is the physical cause underlying the 

 sequence of unusually mild or cold seasons? 

 Such abnormalities have been noted since the 

 earliest times and have been studied by Schott, 

 Stockman, and Henry, and more recently by 

 Dr. C. F. Brooks. The first three showed that 

 no permanent change of temperature is tak- 

 ing place. Dr. Brooks has shown that no other 

 than a chance relationship has existed dm-ing 

 four fifths of the years from 1812 to the pres- 

 ent; the remaining fifth is represented by two 

 series of alternating cold and warm winters 

 attended by similar preliminary seasons. These 

 series begin with 1872-73 and 1917-18, and are 

 of especial interest in connection with their 

 bearing upon generalized long-range forecast- 

 ing. 



Wliat are the highest and lowest tempera- 

 tures ever observed at various stations in the 

 United States? "Zero has not been recorded 

 on the Atlantic Coast south of Chesapeake 

 Bay, on the immediate Gulf Coast, or in the 

 Valley of California." In the northern Plains 

 -60° F. has been recorded. At Greenland 

 Ranch, in the Death Valley, a temperature of 

 134° F. was measured. Key West, Fla., is 

 the only regular Weather Bureau station that 

 has never recorded a freezing temperature. 



Finally, there is the question of the validity 

 of certain beliefs that there are irregularities 

 in the annual march of temperature which 

 tend to persist. The "January thaw," the 

 "May freeze" and "Indian summer" seem to 

 have no counterpart in the annual march of 

 temperature, according to Professor C. F. Mar- 



