174 



NATURE 



[December 8, 1910 



relative amounts of the different dissolved salts also 

 vary widely, these variations being related to climatic 

 and lithological differences. Clarke computes the 

 amount of sodium annually carried down by rivers 

 to be 175,040,000 metric tons, and the total amount 

 of sodium in the sea 14,130x10'^ tons, which gives 

 as a quotient 80,726,000 years. He apparently con- 

 siders possible corrections to be unimportant, or to 

 balance one another, for he believes this crude quotient 

 to be "as probable as any other value that might be 

 chosen." As representing the age of the ocean, he 

 considers this figure, for reasons set forth in Becker's 

 memoir, to be "certainly a maximum." 



The fundamental weakness of all such calculations, 

 whether based on sedimentation or on solvent erosion, 

 lies in the assumption that the present annual rate 

 represents with sufficient approximation the mean rate 

 throughout geological time. To the present writer this 

 consideration deprives the conclusions of even a re- 

 mote relevance to the actual problem. We know, for 

 instance, that, even during the accumulation of a 

 single formation at a given spot, the rate of deposition 

 mav vary widely, and in a shallow-water formation 

 mav be at one time positive and at another negative. 

 To accept the thickness of a formation as a measure 

 of its time of accumulation, with whatever qualifica- 

 tions and allowances, must inevitablv lead to error, 

 and probably to a greatly exaggerated estimate of the 

 rate of sedimentation. Like reasoning applies to all 

 processes of chemical as well as mechanical erosion 

 and deposition, which are necessarily controlled by 

 varying conditions. Even if we could eliminate the 

 effects of relatively rapid and local variations, we have 

 still to consider probable secular changes and others 

 of a broadlv periodic kind. 



A partial recognition of this side of the problem 

 has led Dr. Becker to discard Joly's assumption of a 

 constant rate of increment of sodium in the sea, and 

 to adopt instead a secular change of rate. He lays 

 stress on the fact that at present the felspathic rocks 

 are, over great areas, covered with a blanket of 

 rotten rock in place, which contains onlv a negligible 

 amount of sodium ; and he pictures a distant future, 

 when all massive rocks may be decayed down to sea- 

 level, and addition of sodium to the ocean will prac- 

 ticallv cease. He thus reaches the remarkable con- 

 clusion that the rate of increment of sodium in the 

 sea is progressively declining, and he accordingly re- 

 presents it by a descending exponential expression. 

 The age of the ocean is calculated, according to 

 different hypotheses, as from 74*4 millions of years. 

 The argument is not one which is likely to convince 

 geologists. A decayed crust covering large continen- 

 tal areas must certainly have existed at many past 

 epochs, and, indeed, the present time seems to be 

 peculiarly favoured, in that extensive tracts have been 

 recently scoured by ice. Further, stratified deposits 

 yield more sodium, per square mile, than crystalline 

 rocks, and, throughout geological time as a whole, 

 the sediments have certainly made an increasing pro- 

 portion . of the whole land-surface. Most geologists 

 believe, moreover, that the total area of land-surface 

 has, on the whole, been growing. It would be pos- 

 sible, therefore, to make out a strong case for a 

 secular acceleration of the rate of addition of sodium 

 to the sea. There is another consideration of even 

 more weif^ht. The larger vicissitudes of the earth's 

 history indicate a certain rough periodicity, and there 

 is good reason to believe that we are living" in a time 

 of geological activity above the average. The author 

 himself remarks that the continents stand at present 

 above their average level, which, of course, greatly 

 promotes erosion ; and he also recognises that the 

 recentlv glaciated regions of the globe are contribut- j 



NO. 2145, VOL. 85] 



ing soduim to the ocean at a rate which must raise 

 the average. Unfortunately, he is content to leave 

 these important considerations without discussion, 

 assuming that they are sufficiently offset by an in- 

 creased marine erosion. 



The second part of Dr. Becker's paper, in which he 

 revises Kelvin's refrigeration argument, we must pass 

 over very briefly. It is ingenious in treatment, but 

 involves too many precarious hypotheses to carry 

 much weight. The special feature is that no assump- 

 tion is made relative to the present superficial tem- 

 perature-gradient. This is eliminated by making us(; 

 of Hayford's "level of isostatic compensation," which 

 is computed to lie at a depth (71 miles) beyond any 

 disturbance from radio-activit}\ Of several special 

 cases considered, the author prefers one which gives 

 sixty million years since the consistentior status, and 

 leads to a present temperature-gradient of 1° F. in 

 77 feet. We may take this latter value as a crux of 

 the whole argument. Dr. Becker remarks that it is 

 low as compared with observation, but he fails to see 

 that, for the gradient due to refrigeration, it must 

 certainly be far too high. Here at least radio-activity 

 cannot be left out of consideration, and, indeed, Strutt 

 has maintained that the observed gradient can be 

 wholly accounted for by heat generated in the outer 

 crust of the earth. If we allow some fraction of th-' 

 annual loss of heat to represent secular cooling, it still 

 appears that the age of the earth must be enormously 

 greater than any estimate included in Becker's sup- 

 posititious cases. A. H. 



PROF. ANGELO MOSSO. 



n""HE School of Physiology in Leipzig was the 

 -•■ Mecca that attracted young men from all quar-^ 

 ters of the globe to study physiology under that grea^ 

 master, teacher, and experimenter, Carl Ludwig. 

 steady stream of young, ardent, able, and talented 

 students crossed the Alps from Italy to prosecute re4 

 search and acquire a knowledge of the methods ir 

 use in the Leipzig School. Amongst the earliest oi 

 these Transalpine scholars was L. Luciani — happiljj 

 still amongst us — and a little later came Angel? 

 Mosso, one of the most illustrious of Italian physic 

 legists, whose death at the age of sixty-four the whole' 

 physiological world to-day deplores. He was born 

 on May 31, 1846, in Turin. After studying at his 

 native university — with no advantages of wealth, for- 

 tune, or high social position — he, by the exercise of 

 his own high intellectual and brilliant gifts, soon be- 

 came distinguished amongst his compeers, and he was 

 selected by Moleschott to be his assistant in the 

 university. He also acted as assistant to Prof. M. 

 Schiff in Florence. 



Before coming to study under Ludwig in the early 

 'seventies of last century, Mosso had already pub- 

 lished his well-known researches on the movements 

 of the CEsophagus, and determined in the dog the 

 weight that could be lifted in the process of swallow- 

 ing an olive-shaped ball (1872). In fact, the study of 

 movements of all kinds always proved to him a fas- 

 cinating and fertile subject of study. At an 

 early period of his career he made observations 

 on the movements of the Iris, and he attributed 

 part of the change in size of the pupil to the filling o\ 

 the blood-vessels of the membrane itself. Ludwig set 

 him the problem to study the peculiarities of the move- 

 ments of the vascular wall as they can be inferred 

 from the results of the perfusion of blood through an 

 excised organ, such as the kidney, a method which 

 already had yielded such brilliant results in other 

 organs. His results were published in 1874. 



