310 Proceedings of the Royal Physical Society. 



small pebbles, and might be considered a kind of boulder or 

 stony clay. A portion was immediately bagged for washing 

 and examination afterwards. The rock surface beneath the 

 earth was, as I have said, finely smoothed and striated, and 

 having cleared and dusted two or three square feet, the 

 direction of the striae was taken by compass, and made out 

 to be a few degrees north of west. From the mouldings of 

 the surface we concluded that the ice which had polished 

 and scratched it had come from the west and gone to the 

 east. On examining the rock we had just bared we found it 

 cracked in various directions — doubtless by recent weather- 

 ing since the turf had been removed, and with little difi&culty 

 we loosened a small portion of it, and lifted it up and bagged 

 it. This was afterwards set in Portland cement, and is now 

 on the table for the inspection of the members.* 



Having thus successfully accomplished our mission, I 

 shovelled the earth back into the hollow again, my heart 

 humming Eureka, not loud but deep, befitting the occasion. 

 As a fierce north wind was blowing strongly over the hill 

 top, we slipped down a few yards on the south side of the 

 hill, out of the wind and into the sun, which was shining 

 brightly and pleasantly warm, and discussed our lunch and 

 the facts which our discovery proved. The summit of Aller- 

 muir, my companion at once concluded, could have been 

 glaciated only by ice that had overridden it. That fact there 

 could be no gainsaying — ice in motion being the only agent in 

 nature capable of polishing and striating rock surfaces such 

 as we had just uncovered. If ice, then in what form ? Was 

 it sea ice — in floe or berg — or coast ice ? The answer was 

 no, decidedly no ; — the reasons for which, as Dr Croll had 

 studied the question thoroughly, he readily recited to me, 

 and which may be found set forth at length in the twenty- 

 seventh chapter of his work on " Climate and Time." Land 

 ice was then suggested — not, however, as glaciers formed on 

 hill slopes and flowing down valleys as in the Alps, but land 

 ice in the form of a sheet covering the whole face of the 

 country — hill and valley alike, as is seen in the case of 

 Greenland — and flowing like it from a centre of dispersion 

 * It may be seen in the Edinburgh Museum of Science and Art. 



