452 B. Milne Home — GlaciaUon of the Shetlands. 



markings, wbicli Messrs. Peach and Home founded on as indicating 

 a movement from the S.E., I observed, that "the evidence to show 

 that the movement was from the S.B., and not from the N.W., was 

 not given" (Address 35). 



Messrs. Peach and Home expressed surprise at this remark, as the 

 boulders, being in their opinion transported by the same agent which 

 striated the rocks, aiforded the evidence asked for. 



What I meant was, that not unfrequently strim themselves indicate 

 by their incision on the rock, which end had first been formed. 

 "Where a striation shows a wide or deep marking at one end, and a 

 gradual disappearance towards the other end, the presumption is 

 that the striating agent had begun its work at the first-mentioned 

 end. 



Not one of the striations mentioned by Messrs. Peach and Home 

 appeared to have presented these indications, and therefore I at- 

 tached little value to them. Accordingly, after adverting to what 

 I supposed to be the true bearings of those mentioned by Mr. Peach 

 {senior), I went on to say, that ^^ the more material point" was. 

 that Mr. Peach, when he discovered which was the "polished'" and 

 " storm " side of Heog Hill, at once saw the direction in which the 

 agent had moved, carrying the drift and striating the rocks. 



(2.) Messrs. Peach and Horne have pointed out that, in converting 

 Mr. Peach's magnetic into true bearings, I committed an arithmetical 

 mistake. I admit and regret it. Mr. Peach's bearings having been 

 W.N.W. — I should have stated the true bearings to be E. and W., 

 and not N.W. 



But the mistake is wholly immaterial, and indeed irrelevant, as 

 regards the question at issue, which is, whether the drift came across 

 the Island of Unst from the eastward or from the westward. Messrs. 

 Peach and Horne, alike in Map and Memoir, assert that it came 

 from the eastward. Mr. Peach (senior) saw what satisfied him that 

 it came from the westward. Messrs. Peach and Horne admit this, 

 when (in their last paper) they say (p. 365), "The ice which pro- 

 duced these markings, must have come from east or west. Mr. 

 Peach inferred that the movement had been from the west." 



That is sufficient for my argument. It is not of the slightest 

 consequence, whether the movement was from due W., or W.N.W., 

 or N.W. ; and therefore I was less careful in calculating the exact 

 westerly bearings. 



(3.) Another circumstance is now mentioned by Messrs. Peach and 

 Horne in their last paper, which shows how little reliance is to be 

 placed on the direction of the striations observed by them. They 

 state that in the Island of Unst, " as there was a strong local deflec- 

 tion of the compass, amounting to about 25°, the j)roper direction of 

 the striations was obtained from a party of the Ordnance Survey, who 

 were at work near the spot at the time they were noted " (p. 366). 



This seems to me a circumstance seriously affecting the dependence 

 to be placed on any of the striations recorded by Messrs. Peach and 

 Horne. How they discovered the fact of there being a local com- 

 pass deflection at the place named, is not explained. But similar 



