172 FRAGMENTS OF SCIENCE. 



established between Glen Roy, Glen Glaster, and the 

 upper part of Glen Spean. A common lake would fill all 

 three glens, the level of which would be that of the col D, 

 over which for an indefinite period the lake would pour its 

 water. During this period the lowest Glen Roy road, 

 which is common also to Glen Glaster and Glen Spean, 

 would be formed. Finally, on the disappearance of the 

 ice from the lower part of Glen Spean the waters would 

 flow down their respective valleys as they do to-day. 



Reviewing our work, we find three considerable steps to 

 have marked the solution of the problem of the Parallel 

 Roads of Glen Roy. The first of these was taken by Sir 

 Thomas Dick-Lauder, the second was the pregnant concep- 

 tion of Agassiz regarding glacier action, and the third was 

 the testing and verification of this conception by the very 

 thorough researches of Mr. Jarnieson. No circumstance or 

 incident connected with this discourse gives me greater 

 pleasure than the recognition of the value of these 

 researches. They are marked throughout by unflagging 

 industry, by novelty and acuteness of observation, and by 

 reasoning power of a high and varied kind. These pages 

 had been returned " for press "when I learned that the 

 relation of Ben Nevis and his colleagues to the vapor-laden 

 winds of the Atlantic had not escaped Mr. Jamieson. To 

 him obviously the exploration of Lochaber, and the develop- 

 ment of the theory of the Parallel Roads, has been a labor 

 of love. 



Thus ends our rapid survey of this brief episode in the 

 physical history of the Scottish hills brief, that is to say, 

 in comparison with the immeasurable lapses of time 

 through which, to produce its varied structure and appear- 

 ances, our planet must have passed. In the survey of 

 such a field two things are specially worthy to be taken 

 into account the widening of the intellectual horizon and 

 the reaction of expanding knowledge upon the intellectual 

 organ itself. At first, as in the case of ancient glaciers, 

 through sheer want of capacity, the mind refuses to take 

 in revealed facts. But by degrees the steady contemplation 

 of these facts so strengthens and expands the intellectual 

 powers, that where truth once could not find an entrance 

 it eventually finds a home.* 



* The formation, connection, successive subsidence, and final dis- 

 appearance of the glacial lakes of Lochaber were illustrated in the 



