166 FRAGMENTS OF SCIENCE. 



pilgrimage to the place, and explored pretty thoroughly 

 the roads of tha principal glen. I traced the highest road 

 to the col dividing Glen Roy from Glen Spey, and, thanks 

 to the civility of an ordnance surveyor, I was enabled to 

 inspect some of the roads with * theodolite, and to satisfy 

 myself regarding the common level of the shelves at op- 

 posite sides of the valley. As stated by Pennant, the 

 width of the roads amounts sometimes to more than twenty 

 yards; but near the head of Glen Roy the highest road 

 ceases to have any width, for it runs along the face of a 

 rock, the effect of the lapping of the water on the more 

 friable portions of the rock being perfectly distinct to this 

 hour. My knowledge of the region was, however, far from 

 complete, and nine years had dimmed the memory even of 

 the portion which had been thoroughly examined. Hence 

 my desire to see the roads once more before venturing to 

 talk to you about them. The Easter holidays of 1876 were 

 to be devoted to this purpose; but at the last moment a 

 telegram from Roy Bridge informed me that the roads 

 were snowed up. Finding books and memories poor sub- 

 stitutes for the flavor of facts, I resolved subsequently 

 to make another effort to see the roads. Accordingly last 

 Thursday fortnight, after lecturing here, I packed up, 

 and started (not this time alone) for the North. Next 

 day at noon my wife and I found ourselves at Dalwhinnie, 

 whence a drive of some five-and-thirty miles brought us 

 to the excellent hostelry of Mr. Macintosh, at the mouth 

 of Glen Roy. 



We might have found the hills covered with mist, 

 which would have wholly defeated us; but Nature was 

 good-natured, and we had two successful working days 

 among the hills. Guided by the excellent ordnance map 

 of the region, on the Saturday morning we went up the 

 glen, and on reaching the stream called Allt Bhreac 

 Achaidh faced the hills to the west. At the watershed be- 

 tween Glen Roy and Glen Fintaig we bore northward, 

 struck the ridge above Glen Gluoy, came in view of its 

 road, which we persistently followed as long as it continued 

 visible. It is a feature of all the roads that they vanish 

 before reaching the cols over which fell the waters of the 

 lakes which formed them. One reason doubtless is that 

 at their upper ends the lakes were shallow, and incompe- 

 tent on this account to raise wavelets of any strength to 



