156 FRAGMENTS OP SCIENCE. 
" In the face of these hills," says this writer, " both sides 
of the glen, there are three roads at small distances from 
each other and directly opposite on each side. These 
roads have been measured in the complete parts of them, 
and found to be 26 paces of a man 5 feet 10 inches high. 
The two highest are pretty near each other, about 50 
yards, and the lowest double that distance from the near- 
est to it. They are carried along the sides of the glen with 
the utmost regularity, nearly as exact as drawn with a line 
of rule and compass." 
The correct heights of the three roads of Glen Roy are 
respectively 1,150, 1,070, and 860 feet above the sea. 
Hence a vertical distance of 80 feet separates the two high- 
est, while the lowest road is 210 feet below the middle 
one. 
These " roads" are usually shelves or terraces formed in 
the yielding drift which here covers the slopes of the 
mountains. They are all sensibly horizontal and therefore 
parallel. Pennant accepted as reasonable the explanation 
5\A , of them given by the country people in his time. They 
^ jr thought that the roads " were designed for the chase, and 
^^J^ y that the terraces were made after the spots were cleared in 
lines from wood, in order to tempt the animals into the 
open paths after they were roused, in order that they might 
come within reach of the bowmen who might conceal them- 
selves in the woods above and below." 
In these attempts of " the country people "we have an 
illustration of that impulse to which all scientific knowl- 
edge is due the desire to know the causes of things; and 
' it is a matter of surprise that in the case of the parallel 
roads, with their weird appearance challenging inquiry, 
-' this impulse did not make itself more rapidly and energet- 
ically felt. Their remoteness may perhaps account for 
the fact that until the year 1817 no systematic description 
of them, and no scientific attempt at an explanation of 
them, appeared. In that year Dr. MacCulloch, who was 
then president of the Geological Society, presented to that 
Society a memoir, in which the roads were discussed, and 
pronounced to be the margins of lakes once embosomed in 
Glen Roy. Why there should be three roads, or why the 
lakes should stand at these particular levels, was left unex- 
plained. 
To Dr. MacCalloch succeeded a mafl, possibly not sq 
