August 11, 1905.] 



SCIENCE. 



187 



to pressure without regard to time, while those 

 who find the cyclone the warmer have, with 

 one exception, considered the temperature with 

 relation to the time of maxima and minima of 

 pressure. A treatment of the data used by 

 Teisserenc de Bort according to the method 

 adopted by Clayton, leads the latter to results 

 exactly the opposite of those obtained by the 

 former. 



In order to explain the results found at 

 Blue Hill, Clayton has adopted the hypothesis 

 that there are two causes for areas of low 

 pressure : (1) an area of cold which contracts 

 the air and tends to cause cyclonic circula- 

 tions in the upper air, and (2) an area of 

 warmth which expands the air and tends to 

 cause cyclonic circulations in the lower air. 

 These two cyclones are not necessarily con- 

 nected. Both affect surface pressures, and 

 both probably usually exist simultaneously 

 within a few hundred kilometers of each other, 

 and may form part of one system. The warm- 

 air cyclone of the surface has hitherto received- 

 the most attention. In this somewhat cora- 

 plex relation of upper and lower cyclones, as 

 hypothecated by Clayton, we may find a satis- 

 factory adjustment of conflicting views. 



METEOROLOGY AT COLORADO COLLEGE, COLORADO 

 SPRINGS. 



Meteorology is developing under favorable 

 auspices at Colorado College, under the direc- 

 tion of Professor F. H. Loud. The observa- 

 tory building, erected in 1894, was the gift of 

 Henry E,. Wolcott, Esq., of Denver. There is 

 a full equipment of mfeteorological instru- 

 ments, some of which are exposed on the flat 

 roof of the observatory, while others are placed 

 on the roof of a neighboring building, east of 

 the observatory and on higher ground. Tri- 

 daily eye observations are made, and from the 

 self-recording instruments the conditions at 

 the end of each hour during the twenty-four 

 are determined. Monthly and annual sum- 

 maries for 1904 are contained in the Semi- 

 Annual Bulletin of the Colorado College Oh- 

 servatory (Colo. Coll. Studies; Gen. Ser., ISTo. 

 16; Science Ser., Nos. 39-41; Vol. XL, pp. 

 119-190; April, 1905). In addition, Professor 

 Loud discusses the topography of the district. 



the diurnal changes of atmospheric conditions 

 (illustrated by curves) and the cold wind of 

 October 24, which came at the time of the 

 usual morning increase of temperature and 

 gave a daily maximum at 4 a.m. This wind, 

 which was observed by two parties at high alti- 

 tudes, began with a shallow flow of cold air 

 from the north, in front of an approaching 

 anticyclone. The cold stratum seems to have 

 run beneath the quiet air of the region, lifting 

 it and giving rise to a thin stratum of cloud 

 which resulted from condensation by reason 

 of ascent.' Sometimes these conditions give 

 rise to a slight fall of snow. A paper on 

 ' The Evolution of the Snow Crystal,' by John 

 C. Shedd, embodies some results of studies 

 made during the winter of 1901-02 at Colo- 

 rado Springs. The author believes that the 

 primitive crystal is, for the tabular form, of 

 the 'fern stellar' type, i. e., open in structure 

 and with many branches, while for the col- 

 umnar form it is the hollow column; that the 

 solid tabular, solid columnar or granular 

 forms are the final forms to which all others 

 tend, and that there are two general processes 

 of transformation from primitive to final 

 forms. One process is that of accretion, and 

 the other is that of transformation, in which 

 the losses and gains result in a change in 

 form, but not necessarily in amount of ma- 

 terial, 



NEOLITHIC DEW-PONDS. 



A RECENT study of 'Neolithic D.ew-ponds 

 and Cattle-ways,' by A. J. and G. Hubbard 

 (London, Longmans, Green and Co., 1905), 

 brings out some interesting evidence of the 

 construction of dew-ponds by the early in- 

 habitants of Great Britain. The process of 

 construction was as follows: An exposed posi- 

 tion where springs were absent was selected, 

 and the hollowed surface was covered over 

 with straw or some other non-conducting ma- 

 terial. Over this was spread a thick layer of 

 clay, strewn with stones. Condensation dur- 

 ing the night from the lower air on the cold 

 surface of the clay provided the water-supply 

 for the pond. Springs and drainage from 

 higher ground were avoided, because running 

 water would cut down into the clay surface 



