June 1, 1900.] 



SCIENCE. 



871 



' fragment ' includes a part of the Soutli Downs, 

 a monoclinal ridge of chalk that forms the 

 southern enclosure of the denuded area of the 

 Weald. The ridge is trenched by the conse- 

 quent valley of the Arun, an excellent example 

 of its class ; yet the Arun is merely said to be 

 'a typical river of the Weald,' leaving the un- 

 informed reader entirely in the dark as to the 

 features that it typifies, although a paragraph 

 is allowed to the no more important matter of 

 a comparison of Selsey bill, with two other sa- 

 lients of the south coast. The beautiful mean- 

 ders of the Arun in its transverse valley through 

 the Downs are passed over without explanation 

 and without reference to similar features else- 

 where, although the square cross-roads of Chi- 

 chester are interestingly explained as of Roman 

 origin, and the mean values of hours of sunshine 

 and of atmospheric pressure are properly stated 

 in relation to the values that obtain in other 

 parts of Britain. As to the origin of the Arun 

 valley, we find only the skeptical statement that 

 it " might possibly be explained by supposing 

 that the river * * * course was determined by 

 the original dip slope of the Wealden Dome." 

 Cocking pass, a notch in the Downs west of the 

 Arun gorge in all probability marks the former 

 path of a consequent stream whose head- waters 

 have been diverted to the Arun system by the 

 subsequent Rother, yet no mention is made 

 even of the possibility of such a change, al- 

 though space is found for Reid's venturesome 

 theory that the dry valleys of the Downs were 

 formed during 'the end of the glacial period,' 

 when the usually pervious chalk ' was frozen 

 into hard and impervious rock in which the 

 torrents resulting from the melting of the 

 higher snow cut oufthe valleys'; no consid- 

 eration being here given to the work of ordi- 

 nary subaerial erosion on the chalk during a 

 preglacial time that was long enough to witness 

 the excavation of the interior lowland of the 

 Weald. 



Dr. Mill's paper contains a large amount of 

 well chosen and well presented material. It 

 will probably be taken as a model upon which 

 later essays will be framed. It is therefore all 

 the more to be regretted that physiographic de- 

 scription was not more fully and systematically 

 supplemented by explanation, and that the 



many local types of land and water forms were 

 not presented as members of their class, rather 

 than as (apparently) isolated examples. 



THE PESCADOEBS ISLANDS. 



The Pescadores or Hoko islands, lying be- 

 tween Formosa (Taiwan) and the Chinese coast, 

 are described by Koto (Notes on the Geology of 

 the dependent isles of Taiwan, Journ. Coll. Sci., 

 Imp. Univ., Tokyo, xiii, 1899, pt. 1) as the 

 ragged remnants of a series of nearly horizon- 

 tal basalt sheets with intercalated strata of 

 supposed Tertiary age. The islands and islets, 

 57 in number (besides countless reefs and 

 ledges), are low and tabular or mesa-like, with 

 deep weathered soil on the uplands. Their 

 original area has been much lessened erosion, 

 especially by the attack of the waves, as the 

 uplands descend to the irregular shore line in 

 steep slopes, broken at different levels by the 

 edges of thin basalt sheets. The surface is 

 barren and desolate, ' a quasi-desert, and not 

 an oasis, amidst the green island- world of south- 

 eastern Asia,' a condition that is attributed to 

 the savage violence of the wind, which blows 

 from the northeast during three quarters of the 

 year. The rains of the southwest winds in 

 summer sink into the ground, forming few 

 streams ; erosion at present is chiefly per- 

 formed by the winds and waves. Fringing and 

 barrier coral reefs grow nearly all around the 

 island upon the basaltic shelf. 



W. M. Davis. 



CURRENT NOTES ON 3tETE0R0L0OY. 



CLIMATE OF SAN FRANCISCO. 



Under the direction of the present Local 

 Forecast Official of the Weather Bureau, at San 

 Francisco, Mr. A. G. McAdie, special attention 

 is being paid to studies of local climates in Cali- 

 fornia. The Monthly Review of Climate and Crops : 

 California Section, has thus lately contained re- 

 ports upon the climates of Eureka, Fresno, Los 

 Angeles, Sacramento, San Bernardino, San 

 Diego, San Francisco, Stockton and Visalia. 

 Now there has been issued The Climate of San 

 Francisco, Cal., as Bulletin No. 28, of the 

 Weather Bureau, prepared by A. G. McAdie and 

 G. H. Willson. The records which have been 

 studied go back, in the case of the monthly and 



