106 Mr. J. Croll on Ocean- currents. 



siderable uncertainty prevails regarding some of the data; but, 

 after making the fullest allowance for every possible error, the 

 influence of currents is so enormous that the general conclusion 

 cannot be materially affected. I can hardly think that any one 

 familiar with the physics of the subject would be willing to admit 

 that it is probable that, owing to errors in the data, the effects have 

 been doubled. But even admitting that they have, still it does 

 not materially alter the general conclusion at which we have 

 arrived. The influence of ocean-currents in the distribution of 

 heat over the surface of the globe must still be admitted to be 

 enormous, whether we conclude that owing to them the present 

 temperature of the equator is 55° or 27° colder than it would 

 otherwise be, or the poles 83° or 41° hotter than they would 

 be were there no currents. 



Yea, more, suppose we should again halve the result ; still we 

 should have to admit that, owing to ocean-currents, the equator 

 is about 14° colder and the poles about 21° hotter than they 

 would otherwise be; in other words, we should have to admit 

 that, were it not for ocean-currents, the mean temperature of the 

 equator would be about 100° and the mean temperature of the 

 poles about —21°. 



If the influence of ocean-currents in reducing the difference 

 between the temperature of the equator and poles amounted to 

 only a few degrees, it would, of course, be needless to put much 

 weight on any results arrived at by the method of calculation 

 which has been adopted in this paper ; but when it is a matter 

 of two hundred degrees, it is not at all likely that the general 

 results will be very much affected by any errors which may ever 

 be found in the data. 



Objections of a palseontological nature have frequently been 

 urged against the opinion that our island is much indebted for 

 its mild climate to the influence of the Gulf-stream ; but, from 

 what has already been stated, it must, I presume, be apparent 

 that all objections of that nature are of little avail. The palae- 

 ontologist may detect, from the character of the flora and fauna 

 brought up from the sea-bottom by dredging and other means, 

 the presence of a warm or of a cold current ; but this can never 

 enable him to prove that the temperate and polar regions are not 

 affected to an enormous extent by warm water conveyed from 

 the equatorial regions. For anything that palaeontology can 

 show to the contrary, were ocean-currents to cease, the mean 

 \J annual temperature of our island might sink below the present 

 midwinter temperature of Siberia. What would be the thermal 

 condition of our globe were there no ocean-currents is a question 

 for the physicist ; not for the naturalist. 



