1?2 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 I), 
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- Lander, 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 
