JUXY 9, 1915] 



SCIENCE 



63 



son Physical Laboratory, Harvard Univer- 

 sity. 



The author has been able to reach the wave- 

 length A 600, and finds 7 or 8 lines in the 

 helium spectra between A 900 and A 600, some 

 of the lines being fairly strong. 



14. Unsymmetrical Lines in Tube-Arc and 

 Spark Spectra as an Evidence of a Dis- 

 placing Action in these Sources: A. S. Ejng, 

 Mount Wilson Solar Observatory, Carnegie 

 Institution of Washington. 



The observed effects seem to be harmonized 

 by considering as a necessary condition the 

 presence of electrified particles moving at high 

 velocities, these being produced in the arc and 

 spark by the strong potential-gradients and in 

 the tube-arc by the large consumption of 

 energy. 



15. On the Factorization of Various Types of 

 Expressions: Henry Blumberg, Depart- 

 ment of Mathematics, TJniversity of Ne- 

 braska. 



The methods of E. H. Moore's " General 

 Analysis " are applied to giving a uniform 

 central theory for factorization of different 

 series of expressions. 



16. The Direction of Rotation of Sun-spot 

 Vortices: George E. Hale, Mount Wilson 

 Solar Observatory, Carnegie Institution of 

 Washington. 



Of the two spots in the typical spot-pair the 

 preceding spot in the low-latitude zone is 

 counter-clockwise north, and clockwise south, 

 of the equator; corresponding to the direction 

 of the rotation of terrestrial tornados. In high 

 latitudes the signs are reversed, giving a re- 

 sult which is likely to prove significant in 

 future studies of the sun. 



17. Some Vortex Experiments Bearing on the 

 Nature of Sun-Spots and Flocculi: G. E. 

 Hale and G. P. Luckey, Mount Wilson 

 Solar Observatory, Carnegie Institution of 

 Washington. 



Some of the phenomena of single and mul- 

 tiple sun-spots can be imitated by simple labo- 

 ratory experiments in which vortices are 

 formed in a water tank with an atmosphere of 

 smoke above the water. Such experiments 

 may assist in accounting for certain char- 



acteristic structures and motions of the solar 

 atmosphere. Edwin BrowELL Wilson 



NOTES ON METEOSOLOGY AND 

 CLIMATOLOGY 



THE WEATHER ELEMENT IN AMERICAN CLIMATES 



Climate may be defined as average weather. 

 Thus Professor R. DeC. Ward is fully justi- 

 fied in opening a discussion of the climates of 

 the United States with a chapter on the 

 Weather Element in American Climates.-'- 

 Winter weather is characteristically change- 

 able. The rapid motions of strong cyclones 

 and anticyclones, with the sun low in the heav- 

 ens, places the weather primarily under cy- 

 clonic control. On the other hand, in sum- 

 mer, when cyclone activity is weak and the 

 sun is high in the sky, the weather under the 

 regular solar control is much the same from 

 day to day. In spring and autumn, the inter- 

 play of these two controls is strikingly appar- 

 ent. A cyclone approaches, giving rise to 

 easterly winds, cloudy weather and rain, with 

 a falling barometer. The solar control van- 

 ishes. However, as the storm passes and west- 

 erly winds follow, the clouds break away and 

 the diurnal control again dominates. 



Weather types depend largely on the origin 

 of the winds which flow towards passing cy- 

 clones. Thus, on the eastern coast easterly 

 winds are usually damp and westerly ones 

 dry. In winter, the easterly and southerly 

 winds are warmer than those from the west 

 and north, but in summer the west winds are 

 generally warmer than the east. The same 

 holds true for the central valleys and great 

 plains except that the east winds of summer 

 are often warm. Furthermore, the winter cy- 

 clones fail to bring much precipitation to the 

 great plains because of the prevailing cold. 

 On the Pacific coast, west winds are damp and 

 equable; while the land winds from the north 

 and east are dry, and bring the extremes of 

 temperature. 



The frequency with which different weather 

 tyi)es occur, depends primarily on the paths 

 and frequency of cyclones. In winter, cyclone 

 paths cover practically the whole United 



1 Annals of the Association of American Geog- 

 raphers, Vol. IV., 1915, pp. 3-54. 



