268 



NATURE 



\7uly 4, 1878 



of cooling down was reached, because there was no water to 

 form them ; and no life coitld have existed on the earth until it 

 cooled down to the latter temperature. 



Thus we find in the Arctic regions, the following successive 

 temperatures : — 



I. — 212° F Boiling water. 



2, — 122° F Coagulation of albumen, 



3. — 68° F Triassic and Jurassic periods. 



(Climate of Gulf of Mexico.) 



4. — 48° F Miocene tertiary period. 



(Climate of Lombardy.) 



^, — 32° F (Climate of Labrador.) 



6. — 0° F Present climate. 



The interval between the first and second corresponds to the 

 azoic rocks ; that between the second and third to the palaeozoic 

 rocks ; and that between the third and fourth to the neozoic 

 rocks. Now, although we do not know the coefficient that 

 fixes the rate of cooling of the hot earth suspended in cold space, 

 we know the law of such cooling, and can compare, by calcula- 

 tion, the proportions of the foregoing intervals of time with each 

 other. 



When this calculation is 'made we obtain : — 



Azoic time (2I2°-I22°) ... .... 33-0 per cent. 



Palaeozoic time ... (122°- 68°) i,vo „ 



Neozoic time ... (68°- 48°) 26*0 ,, 



loo'o ,, 



In my former note, iii. p. 54S,* I have given a table of the 

 approximate thicknesses of the several strata in Europe. That 

 table was prepared, with the assistance of the late Prof. Phillips, 

 many years ago, and is not as complete as it might be. I there- 

 fore sought the assistance of Prof. Edward Hull, Director of 

 the Geological Survey of Ireland, and with his help I have con- 

 structed an improved table. 



Converting the maximum thicknesses recorded in that table 

 into percentages, and comparing them with the percentages of 

 time found from the theory of a cooling globe, we find — 



Scale of Geological Time. 



Period. 



Azoic 

 Palaeozoic 

 Neozoic .. 



Total 



From Theory o£ 

 Cooling Globe. 



33 'o per cent. 

 41-0 „ 

 26*0 „ 



lOO'O 



From Maximum 

 Thickness of Strata. 



34-3 per cent. 



42"5 „ 

 23*2 „ 



ICO'O 



The agreement between these figures, derived from entirely 

 independent sources, is remarkable, and tends to justify the 

 principle held by many geologists, that — 



The proper relative measure of geological periods is the maximum 

 thickness of the strata formed during those periods. 



This is equivalent to supposing the rate of deposition of strata 

 to have been constant during the period contained in the table, 

 which is probable enough on other grounds ; for, although the 

 rock-making forces were greater when the heat was greater, it 

 must be remembered that the land surfaces to be denuded were 

 smaller, and that the sea bottoms, on which the debris was to be 

 spread, were also greater. The calculation founded on the 

 theory of the cooling globe cannot with safety be carried down 

 to near the point of equilibrium temperature, which is the 

 Fahrenheit zero (for the Arctic regions under consideration) ; 

 but we may, without risk, extend the calculation from 48° F, to 

 32° F. ; that is, we may estimate the interval of time from the 

 miocene tertiary epoch, when the Parry Islands and Northern 

 Greenland enjoyed a Lombardic climate, to the epoch (probably 

 long past) when those districts suffered a climate like that of 

 Labrador, but better than that they now have. 



The result of the calculation, when reduced to the same scale 

 as that used in the table, is 32 per cent., a result, the importance 

 of which will be better seen by the following propositions which 

 flow from it : — 



I. A greater interval oj time now separates us from the miocene 

 tertiary epoch than that which was occupied in producing all the 



» Proc'.'S.. S., December 20 1877 



secondary and tertiary strata, from the triassic to the miocene 

 epoch. 



2. The enormous interval of time that separates us from the 

 miocene epoch affords ample opporttimty for the development of the 

 gigantic inammals, ivhich are commonly supposed to have some- 

 what suddenly made their appearance on all our continents, and 

 to have disappeared as suddenly. 



All the foregoing facts point to the conclusion that the present 

 condition of the earth's surface is profoundly different from its 

 condition in the geological periods when climates depended 

 chiefly on the internal heat of the earth, and not on that of the 

 sun, as at present. 



The following table contains estimates of the number of years 

 required by the several rivers to scrape off one foot from their 

 respective rain-basins, and carry the materials to the sea, where 

 it is spread out on the sea bottoms by ocean currents. The 

 figures are obtained by carefully measuring, at frequent intervals, 

 the total discharge of water and the total weight of mud held in 

 suspension. This weight of mud, reconverted into surface 

 rock, must cover the entire rain-basin to a depth of one foot 

 spread uniformly. 



Rates of Denudation of Rain-Basins Lowered One Foot. 



Ganges 2,358 years. 



Mississippi 6,ckx) ,, 



Hoang Ho 1,464 >, \ 



Yangtse Kiang 2,700 ,, 



Rhone 1,528 ,, 



Danube 6,846 ,, 



Po ' 729 ;, 



Mean 3,090 ,, 



From this table it appears that atmospheric agencies are 

 capable, at present, of lowering the land surfaces at the rate of 

 one foot per 3,000 years ; but since the sea bottoms are to the 

 land surfaces in the proportion of 145 to 52, the rate at which 

 (under present circumstances) the sea bottoms are silted up, that 

 is to say, the present rate of formation of strata, is one foot in 

 ?),6i6 years. If we admit (which I am by no means willing to 

 do) that the manufacture of strata in geological times proceeded 

 at ten times this rate, or at the rate of one foot for every 861 '6 

 years, we have for the whole duration of geological time, down 

 to the miocene tertiary epoch, 



86i*6 X 177,200 = 152,675,000 years,* 

 To this must be added at least one-third, as before shown, to 

 bring in the period from the Miocene Tertiary to the time when 

 the Parry Islands and North Greenland had the climate of 

 Labrador. 



This gives for the whole duration of geological time a mini- 

 mum of ttuo hundred millions of years. 



ACTION OF DRUGS ON THE LIVER"^ 



pROF. RUTHERFORD'S paper described the concluding 

 -■■ results of the long research undertaken by him on 

 "The Biliary Secretion with Reference to the Actions of 

 Cholagogues." He pointed out the difficulties which had 

 rendered it impossible for physicians to arrive at precise 

 knowledge as to the actions of substances on the liver from 

 observations on the human subject, and the imperative neces- 

 sity for having recourse to experiments on animals, whereby 

 some of the factors that complicate the case in the uninjured 

 system may be eliminated, and definite knowledge regarding the 

 action of agents on one of the most important organs of the body 

 instituted for the vague guesses of twenty centuries. Several 

 previous investigators had striven by experiments on animals to 

 settle this question, but all had failed owing to the faulty 

 character of the methods employed. By a new and precise 

 method of continuous collection of the bile, and measurement of 

 the amount secreted every fifteen minutes — with a careful elimi- 

 nation of disturbing factors — the whole physiological pharma- 

 cology of the liver has been worked out by Prof, Rutherford — as 

 far as it seems at present desirable to proceed. The actions of 

 as many as forty-six substances on the bile-forming function of 

 the liver have been investigated, and results of much im- 

 portance for rational therapeutics obtained. Some of the 



1 The coefficient 177,200 is the total number of feet of maximum thickness 

 of all the known stratified rocks. 



2 Abstract of paper read at the Royal Society of Edinburgh on June 17, 

 by Prof. Wm. Rutherford, F.R.S., Prof. Sir Wyville Thomson (m the 

 absence of Sir Wm. Thomson) in the chair. 



