480 Correspondence — Dr. James C roll— Rev. W. Doxones. 



INTEEGLACIAL PERIODS. 



Sik, — In the last Number of this Magazine Mr. McGee does me 

 the honour to refer to the theory which I have advanced to account for 

 those warm interglacial periods, of which the records are preserved 

 in most highly glaciated regions which have been examined with 

 adequate attention. As Mr. McGee appears to have misunderstood 

 what I have written, and to have fallen into a misapprehension in 

 regard to the melting of polar ice, perhaps you will kindly allow 

 me, for the sake of those not familiar with the subject, to point out 

 where he has gone wrong. I have not, as he supposes, assumed 

 that the comparative disappearance of ice on the warm hemisphere, 

 during the period of high excentricity, is due to any additional heat 

 derived from the sun in consequence of the greater length of the 

 summer, for there is no such increment. A shortening of the winter, 

 or snow-falling season, would no doubt considerably diminish the 

 quantity of the ice ; but the mere lengthening of the summer would 

 have little effect. The real and effective cause of the disappearance 

 of the ice was the enormous transference of equatorial heat to 

 temperate and polar regions by means of ocean currents. My 

 theory holds that the polar ice was melted mainly b}' heat carried 

 from equatorial regions, rather than by the direct rays of the sun. 



Mr. McGee calculates that only -615 of a foot of polar ice would 

 be melted annually ; but there is no reason why there may not have 

 been more than twenty times that quantity. James Croll. 



PALEOLITHIC IMPLEMENT FOUND IN DEVONSHIRE. 

 Sik, — About a month ago I had the good fortune to find a palaeo- 

 lithic implement in the parish of Kentisbeare. It is, I believe, the 

 first which has been found in the valley of the Culm. Some time 

 ago Mr. H. B. "Woodward suggested to me the probability that 

 paleolithic implements might be found here. "When, therefore, his 

 forecast was verified, I wrote to him informing him of the fact, and 

 I am now writing to you at his suggestion. 1 found it on a heap of 

 stones collected from a field and piled up in the corner of the field 

 for removal as road metal. It is of bluish chert, weathered white. 

 The field is one only lately brought into cultivation, has a thin 

 peaty soil, and is situated near the centre of Ordnance Sheet XXL, 

 where the words " Kentisbere Moor " occur ; and its exact position 

 would be about the middle of the word " Moor." It must have 

 lain at no great distance beneath the surface, and have either been 

 brought up by the plough, or by ditching and draining work. I have 

 shown it to Mr. D'Urban, Curator of the Albert Memorial Museum 

 at Exeter, and to Mr. P. 0. Hutchinson, of Sidmouth, the latter 

 of whom has kindly taken the inclosed rubbing. As, however, 

 the rubbing does not quite correctly represent the shape (for the 

 surface when spread out will of course slightly exceed the actual 

 breadth) I have traced its outline, and shown the extreme length 

 and breadth. 1 W. Downes. 



Kentisbeare, Colltjmpton, Devon, Sept. 12, 1879. 



1 The implement agrees closely with that drawn in Dr. John Evans's invaluable 

 work on Ancient Stone Implements, plate ii. fig. 17. — Edit. Geol. Mag. 



