ESSAYS 311 



found to determine in reality all the primary conditions of development ; so that 

 we come to have a dual problem — (a) How high can the increase in complexity 

 become (b) in face of continued heat radiation ? 



With regard to (a) taken in itself, I do not see that we can as yet affirm any 

 limits whatever to khe advance— just as any prediction (supposing such possible) 

 of the impossibility of the advent of Life from the inorganic world, or the evolu- 

 tion of Man from Protozoa, would have been falsified by the event,' so we cannot 

 yet (if ever) assert that any given natural system 2 has no possible complement 

 elsewhere in the universe. 



(b) But, admitting this general principle, continued heat radiation may still be 

 held ultimately to terminate all such changes. But against this may be placed 

 the fact that, though the assumed redistributions of temperature are such that 

 instead of a system of localised high temperatures there will be uniformity, it does 

 not therefore at once follow that this final temperature will be fatal to all change ; 

 equally probably it may prove to be a temperature optimal for at least some kinds 

 of change. So that the evolution of heat in exothermic reactions has a further 

 advantage, the resultant compounds being stable and persistent, the liberated heat 

 at the same time tends to establish a uniform medium temperature which, being 

 certainly lower than stellar temperatures, is probably optimal for these same stable 

 substances and their combinations. Again, the rate of temperature fall is asymp- 

 totic — the lower the temperature the more slowly does any given fall proceed ; 

 while at the same time there is substituted for rapid etherial radiation transmission 

 through gaseous media of very low conductivity 3 — two factors plainly tending to 

 maintain a medium uniform temperature. 



In short, to regard the collective heat interchanges of the universe as a " loss " 

 is plainly wrong ; for the heat, though certainly lost by some systems while gained 

 by others, still remains within the universe itself, only under conditions of 

 uniformity instead of localised extremes ; and, as for the solar system, in which 

 humanity is specially interested, it is certainly possible that the sun's failing heat 

 may be supplemented by its entrance into some younger stellar combination, the 

 probability being that stellar motions are regulated somewhat as are the planetary. 



THE DENUDATION OF THE WEALD : A Defence of Existing 



Theories (Henry Bury, F.G.S.). 



In the April number of Science Progress there appeared a paper by Major 

 R. A. Marriott, entitled "The Downs and the Escarpments of the Weald: A 

 New View of their Geological History"; and, as it contains numerous strictures 

 on geologists for having overlooked facts and inferences with which they have, in 

 truth, long been familiar, it may be permitted to one who still prefers the older 

 views to offer a few criticisms. 



To the student of physical geography the two points in the Wealden Area 

 which most require explanation are its escarpments and its transverse rivers. On 

 all sides except that open to the sea the area is bounded by a range of chalk hills 



1 On purely philosophical grounds I think it can be shown that in a systematic 

 universe this continuous increase in complexity is logically inevitable. 



' Which need not be material only ; as development advances the newer 

 categories — vital, intelligent, social — become more prominent as against the back- 

 ground of the older. 



3 That of air, e.g , is 20,000 times less than that of copper (Maxwell, op. cit., 

 V- 345)- 



