Solar Eclipse of July 28, 1851. Ill 



in the transmission of the " Suggestions" should have pre- 

 vented me from making arrangements in time for the packet, 

 and that, notwithstanding the energetic assistance which 

 was accorded me by His Excellency Baron TitofF, and by the 

 officers of the Perseus, we were unable to attain the principal 

 object of our mission. There is, however, this consolation, 

 that, as the Russian astronomers had made complete ar- 

 rangements, no loss to science has accrued from our misad- 

 venture. 



Constantinople, October 2, 1861. 



On the Scratching of Bocks by the passage over them of Sharp 

 Detrital Matter. By Lieut.-Colonel Portlock, F.R.S., 

 President of the Geological Society of Dublin. 



As the old opinion regarding the effect of the passage of 

 detritus over the surface of rocks in forming the scratchings, 

 &c., so generally observed, is again brought forward by our 

 friend the present President of the Geological Society of 

 Dublin, we doubt not our readers will be interested by the 

 following details, as given in Colonel Portlock's Address,* 

 which has just reached us. 



" In my communication on Bantry Bay I brought under your 

 notice one of those examples of the scratching of rocks, by 

 the passage over them of sharp detritic matter, the surface 

 having been previously worn smooth and partially polished 

 by a similar action. The example, which I described from 

 my own personal observation, was taken from one of those 

 bluff clay banks so common in Bantry Bay, the interior por- 

 tion of which — meaning that part within Whiddy Island — 

 appears to have been formed by denudation of a compara- 

 tively recent date, or subsequent to the formation of post- 

 tertiary deposits. The wear of this great mass of gravelly 

 clay studded with boulders, or, in other words, of boulder- 

 clay, is still continuing, and must continue, so long as any 



* Vide Journal of the Geological Society of Dublin, vol. v., Part Ist, 1861. 



