122 



SCIENCE 



[N. S. Vol. XXVI. No. 656 



Where the latter condition exists, the surface 

 above the subterranean passage may subside 

 by solution, producing a ravine of solution. 

 Thousands of such exist over the limestone 

 region of northern Arkansas and southern 

 Missouri, known in geological literature as 

 th& Boone chert area. 



These ravines have been discussed by the 

 ■writer under " Valleys of Solution in North- 

 ern Arkansas.'" Wide observation since the 

 time of writing the above article has con- 

 firmed the belief that the ravines have their 

 origin from solution, but has modified the 

 opinion therein expressed as to their method 

 of development. Instead of beginning at the 

 mouth and developing backward, the usual 

 method was that of starting with sink-holes, 

 well up on the hillside. The drainage from 

 these sink-holes was along subterranean, tubu- 

 lar passages, to the bases of the hills. The 

 gradual subsidence from solution, of the rocks 

 above the subterranean drainage lines, resulted 

 in the numerous striking ravines that form 

 such a conspicuous topographic feature of the 

 region mentioned. 



A. H. Purdue 



Univeksitt of Arkansas, 

 Fayettevili^, Akk. 



QUOTATIONS 



THE FUTURE OF THE TROPICS 



What the comparatively new science of bac- 

 teriology has accomplished for mankind 

 could never have been foreseen a few years 

 back, and even now we probably have a very 

 inadequate idea of its possibilities. The re- 

 cently expressed opinion of Colonel W. T. 

 Gorgas, that within the next two or three cen- 

 turies the tropical countries, which ofier a 

 much greater return for man's labor than do 

 the temperate zones, will be settled by the 

 white races, and that the centers of population 

 and civilization be transferred to the equa- 

 torial regions, may not prove a strictly cor- 

 rect prophecy, but its possibility can not be 

 denied, a priori, as once it would have been. 

 The discovery of the malaria germ and of the 

 transmission of it and of that of yellow fever 



' Journal of Geology, Vol. IX., No. 1, January- 

 February, 1901, pp. 47-50. 



by mosquitoes has abolished the principal 

 drawbacks to the habitability of these regions 

 by the white races to a very great extent, and 

 opened for the use of civilized man large por- 

 tions of the earth's surface that were formerly 

 practically forbidden to him. The question, 

 of course, still remains to be settled whether 

 the white man can retain his physical stamina 

 and energy through residence in the tropics 

 for many generations, and whether the mere 

 conquest of pathologic germs is all that is 

 required. The productiveness of tropical 

 regions is of itself a drawback. The average 

 man works only from necessity, and what 

 renders mere existence the easier does not 

 necessarily tend to the higher development of 

 the race. It was Sir Charles Dilke, we believe, 

 who once called the banana the curse of the 

 tropics, and held that where it abounded 

 human progress and ambition disappeared. 

 There is some truth in this, but it may not be 

 an absolute truth. It is not likely, however, 

 that the tropics will be the leading centers of 

 civilization in the future. The temperate 

 zones, where the struggle for existence brings 

 out the higher abilities of man, will always 

 dominate, and it is not improbable that the 

 tropics will be the recourse of the pervasive 

 yellow races rather than of the white. There 

 is every prospect that with our almost certain 

 conquest of the pathologic conditions that 

 exist in those regions their utility to mankind 

 will be vastly increased and that higher civili- 

 zations than now occupy those lands will be 

 developed. We may not be able to look on the 

 tropics as a permanent home for the best of 

 the ruling white races, even two or three 

 centuries hence, but there is hardly any ques- 

 tion but that they will be much more habit- 

 able and useful than they have been in the 

 past. — Journal of the American Medical As- 

 sociation. 



CURRENT NOTES ON METEOROLOGY AND 

 CLIMATOLOGY 



ROYAL METEOROLOGICAL SOCIETY'S LECTURES 



The Council of the Eoyal Meteorological 

 Society in 1905 appointed a lecturer " to give 

 information on meteorological subjects to 



